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= TinkerPop3 CHANGELOG

== TinkerPop 3.5.0 (The Sleeping Gremlin: No. 18 Entr'acte Symphonique)

image::https://raw.githubusercontent.com/apache/tinkerpop/master/docs/static/images/gremlin-sleeping-beauty.png[width=185]

[[release-3-5-2]]
=== TinkerPop 3.5.2 (Release Date: January 10, 2022)

This release also includes changes from <<release-3-4-13, 3.4.13>>.

* Added an `AnonymizingTypeTranslator` for use with `GroovyTranslator` which strips PII (anonymizes any String, Numeric, Date, Timestamp, or UUID data)
* Added support for `g.tx()` in Python.
* Added logging in in Python.
* Added `tx()` syntax to `gremlin-language`.
* Fixed shutdown cleanup issue in Python aiohttp transport layer.
* Added a `NoSugarTranslator` translator to `PythonTranslator` which translates Gremlin queries to Python without syntactic sugar (ex `g.V().limit(1)` instead of `g.V()[0:1]`)
* Added support for `g.Tx()` in .NET.
* Added support for `with()` constant options to `io()`.
* Changed `GroovyTranslator` to generate code more compatible to Java with `Date` and `Timestamp`.
* Fixed bug in the processing of the `io()` step when constructing a `Traversal` from the grammar.
* Added the `ConnectedComponent` tokens required to properly process the `with()` of the `connectedComponent()` step.
* Fixed `DotNetTranslator` bugs where translations produced Gremlin that failed due to ambiguous step calls to `has()`.
* Fixed bug where `RepeatUnrollStrategy`, `InlineFilterStrategy` and `MessagePassingReductionStrategy` were all being applied more than necessary.
* Modified grammar to accept the `datetime()` function so that Gremlin scripts have a way to natively construct a `Date`.
* Ensured `PathRetractionStrategy` is applied after `InlineFilterStrategy` which prevents an error in traverser mapping in certain conditions.
* Deprecated `JsonBuilder` serialization for GraphSON and Gryo.
* Added `ProductiveByStrategy` to ensure consistency of `by()` modulator behaviors when child traversal arguments contained no elements.
* Changed drivers to once again send the previously deprecated and removed "close" message for sessions.
* Modified `fold()` to merge `Map` instances with `addAll`.
* Allowed `null` string values in the Gremlin grammar.
* Fixed support for `SeedStrategy` in the Gremlin Grammar.
* Fixed bug in `Translator` of `gremlin-javascript` around array translation.
* Fixed bugs in `PythonTranslator`, `JavascriptTranslator` and `DotNetTranslator` when translating `TraversalStrategy` objects to Javascript.
* Prevented exception with `hasLabel(null)` and `hasKey(null)` and instead filter away traversers as these structural components can't ever be null.
* Improved handling of `null` when passed to `P` predicates.
* Handled `null` for mathematical reducing operations of `sum()`, `mean()`, `max()` and `min()`.
* Allowed `null` values in `Memory` for `GraphComputer`.
* Allowed `null` assignment in `withSideEffect()`.
* Allowed labelling of steps that emit a traverser carrying `null`.
* Fixed bug in filtering for `null` property key arguments to `valueMap()`, `elementMap()`, `properties()` and `values()`.
* Modified grammar to allow a call to `within()` and `without()` with no arguments.
* Fixed problems with `inject(null)` variations where `null` was the only value being submitted.
* Fixed problem with `GroovyTranslator` and `inject(null,null)` which could be interpreted as the Groovy JDK extension `inject(Object,Closure)`.
* Fixed error where certain variants of `inject()` with `null` might not properly construct a traversal in .NET.
* Prevented exception with  `hasValue(null)` and allowed filtering as expected.
* Refined `DotNetTranslator` to be more explicit with `null` arguments to ensure that the right overloads are called.
* Created `GremlinParser` to construct `Traversal` objects from `gremlin-language`.
* Added `GremlinLangScriptEngine` as a `GremlinScriptEngine` implementation that users the grammar and `JavaTranslator` to evaluate Gremlin.
* Added getter method for `bypassTraversal` in `AbstractLambdaTraversal`.
* Added support for custom GraphBinary types in .NET.
* Removed some unnecessary exception wrapping around `gremlin-driver` errors now producing a more immediate view of the actual error cause.

==== Bugs

* TINKERPOP-2569 Reconnect to server if Java driver fails to initialize
* TINKERPOP-2585 Traversal failed for different strategies order
* TINKERPOP-2589 XML External Entity (XXE) vulnerability
* TINKERPOP-2597 NullPointerException while initializing connection pool
* TINKERPOP-2598 within(null) NPE
* TINKERPOP-2603 TinkerGraph sometimes could not query float values.
* TINKERPOP-2609 HTTP returns serialization exceptions for the GraphTraversalSource
* TINKERPOP-2621 toString for traversals such as within with empty array returns empty string as argument instead of brackets
* TINKERPOP-2626 RangeGlobalStep closes traversal prematurely
* TINKERPOP-2649 Unable to translate gremlin query to java
* TINKERPOP-2658 Translator in gremlin-javascript has trouble with array arguments
* TINKERPOP-2662 Unclosed client session and stacktrace pops up when cleanup is missed
* TINKERPOP-2670 JavaDocs do not build when using JDK 11

==== Improvements

* TINKERPOP-2504 Intermittently failing server/driver integration tests
* TINKERPOP-2555 Support for remote transactions in Python
* TINKERPOP-2556 Support remote transactions in .NET
* TINKERPOP-2570 Support custom type in GraphBinary for .NET
* TINKERPOP-2582 Construct traversals from gremlin-language
* TINKERPOP-2583 Make gremlin-groovy processing optional in Gremlin Server
* TINKERPOP-2591 Administrative adjustments to gremlint site
* TINKERPOP-2592 Align the style guides
* TINKERPOP-2596 datetime function
* TINKERPOP-2605 Further enforce and refine null semantics
* TINKERPOP-2615 Expand testing of path() with null values
* TINKERPOP-2616 Provide better exceptions with SSL related failures *(breaking)*
* TINKERPOP-2620 Clean up NullPointerExceptions related to null arguments on property related steps
* TINKERPOP-2630 Clarify that a server cannot support Graphson1.0 over HTTP
* TINKERPOP-2632 Netty 4.1.61 flagged with two high severity security violations
* TINKERPOP-2637 Enhance logging in the Python
* TINKERPOP-2646 Make .NET StreamExtensions public for GraphBinary
* TINKERPOP-2656 Provide a no syntax sugar translator for python
* TINKERPOP-2660 Bring back close message for drivers
* TINKERPOP-2666 Create an anonymizing Translator for logging traversals without user data
* TINKERPOP-2667 Allow fold() with addAll to work on Map
* TINKERPOP-2668 Updating aiohttp requirements at germin-python due to vulnerability
* TINKERPOP-2669 Netty 4.1.61 flagged with medium severity security violations
* TINKERPOP-2671 Add tx() support to grammar

[[release-3-5-1]]
=== TinkerPop 3.5.1 (Release Date: July 19, 2021)

This release also includes changes from <<release-3-4-12, 3.4.12>>.

* Added support for `g.tx()` in Javascript.
* Fixed bug in Javascript error message related to validating anonymous traversal spawns.
* Changed close of Python and Javascript connections to no longer send a "close message" as the server no longer acknowledges it as of 3.5.0.
* Fixed bug where the `Graph` instance was not being assigned to child traversals.
* Removed sending of deprecated session close message from Gremlin.Net driver.

==== Bugs

* TINKERPOP-2358 Potential connection leak on client disposing
* TINKERPOP-2554 Extracting step metrics from ProfileStep throws NPE if the step was not triggered
* TINKERPOP-2565 GraphMLWriter does not check vertexLabelKey conflict
* TINKERPOP-2566 Incomplete error message in bytecode step generation
* TINKERPOP-2568 Graph instance not set for child traversals
* TINKERPOP-2578 Set arguments to P within/without are wrapped in List
* TINKERPOP-2579 EventStrategy doesn't work with anonymous traversal
* TINKERPOP-2580 Update the custom DSL documentation

==== Improvements

* TINKERPOP-2548 Add getter for indexer used in IndexStep
* TINKERPOP-2551 Setup scripts to publish Gremint to npm
* TINKERPOP-2557 Support remote transactions in Javascript
* TINKERPOP-2559 Stop sending the close message for .NET
* TINKERPOP-2560 Stop sending close message for Python
* TINKERPOP-2561 Stop sending close message in Javascript
* TINKERPOP-2576 Setup automatic updates via Dependabot for Gremlin.NET
* TINKERPOP-2577 Remove unused test coverage dependencies from Gremlin.NET

[[release-3-5-0]]
=== TinkerPop 3.5.0 (Release Date: May 3, 2021)

This release also includes changes from <<release-3-4-11, 3.4.11>>.

* Changed transport implementation to use AIOHTTP instead of Tornado for gremlin-python.
* Added max_content_length and unit test for it in gremlin-python.
* Removed compression_option support for transport in gremlin-python.
* Fixed event loop issues and added unit test for it in gremlin-python.
* Fixed DriverRemoteConnection multithreading issues and added unit test for it in gremlin-python.
* Fixed heartbeat timeout issues and tested with local server manually for gremlin-python.
* Fixed build errors emitted for gremlin-python (asyncio task destroyed but is pending error).
* Added `gremlin-language` module.
* Allowed the possibility for the propagation of `null` as a `Traverser` in Gremlin.
* Added a fully shaded version of `gremlin-driver`.
* Exposed websocket connection status in JavaScript driver.
* Fixed a bug where spark-gremlin was not re-attaching properties when using `dedup()`.
* Fixed a bug in `WsAndHttpChannelizer` pipeline configuration where failed object aggregation could not write back HTTP responses.
* Ensured better consistency of the use of `null` as arguments to mutation steps.
* Added a `ResponseStatusCode` to indicate that a client should retry its request.
* Added `TemporaryException` interface to indicate that a transaction can be retried.
* Prevented `TraversalStrategy` instances from being added more than once, where the new instance replaces the old.
* Improved error message for `addE()` when the `from()` or `to()` does not resolve to a `Vertex`.
* Improved error message for `addE()` when cardinality is specified on `property()` assignments.
* Allowed `property(T.label,Object)` to be used if no value was supplied to `addV(String)`.
* Dropped support for .NET Standard 1.3 in Gremlin.Net. Only .NET Standard 2.0 is supported starting with this version.
* Added GraphBinary support for .NET.
* Added `UnifiedChannelizer` which exposes HTTP and Websockets connections and processes both sessionless and in-session requests with the same `gremlinPool`.
* Bounded the `gremlinPool` in Gremlin Server to enforce rate limiting which will then produce a `TOO_MANY_REQUESTS` response status code.
* Switched from `Newtonsoft.Json` to `System.Text.Json` as the JSON library for Gremlin.Net.
* Allowed additional arguments to `Client.submit()` in Javascript driver to enable setting of parameters like `scriptEvaluationTimeout`.
* Gremlin.Net driver no longer supports skipping deserialization by default. Users can however create their own `IMessageSerializer` if they need this functionality.
* Supported deserialization of `dict` and `list` as a key in a `dict` for Python.
* Changed the aliased `Client` to proxy `close()` methods to its underlying client.
* Added support for remote `g.tx()` usage.
* Added support for bytecode-based sessions.
* Added a `Graph.Feature` for `supportsNullPropertyValues`.
* Modified `TokenTraversal` to support `Property` thus `by(key)` and `by(value)` can now apply to `Edge` and meta-properties.
* Added `SeedStrategy` to allow deterministic behavior for `coin()`, `sample()` and `Order.shuffle`.
* Added `Grouping` step interface.
* Added `TraversalParent.replaceTraversal()` which can replace a direct child traversal.
* Added `ByModulatorOptimizationStrategy` which replaces certain standard traversals w/ optimized traversals (e.g. `TokenTraversal`).
* Improved `IdentityRemovalStrategy` by accounting for `EndStep` situations.
* Added `IdentityRemovalStrategy` to the standard list of `TraversalStrategies`.
* Modified `PathRetractionStrategy` to leave labels more often with `match()` cases to return more consistent results.
* Refactored `MapStep` to move its logic to `ScalarMapStep` so that the old behavior could be preserved while allow other implementations to have more flexibility.
* Modified TinkerGraph to support `null` property values and can be configured to disable that feature.
* Modified `null` handling in mutations to be consistent for a new `Vertex` as well as update to an existing one.
* Enforced use of anonymous child traversals.
* Removed support for Python 2.x in gremlinpython.
* Upgraded to Apache Commons Configuration2.
* Renamed `StoreStep` to `AggregateLocalStep`.
* Renamed `AggregateStep` to `AggregateGlobalStep`.
* Renamed `SERVER_ERROR_SCRIPT_EVALUATION` to `SERVER_ERROR_EVALUATION` given that this response code applies to remote traversals as well as scripts.
* Refactored `TraversalStrategies` to implement `Iterable`.
* Refactored `Traversal` semantics to always expect `EmptyStep` as a parent if it is meant to be the root `Traversal`.
* Configured GraphBinary as the default binary serialization format for the Java Driver.
* Configured GraphSON 3.0 as the default text serialization format when no serializer can be determined.
* Configured GraphSON 3.0 as the default setting for the `GraphSONMapper`.
* Added `JavascriptTranslator` for Java.
* Added `DotNetTranslator` for Java.
* Added Groovy `Translator` for Python.
* Fixed bug in `PythonTranslator` for processing `TraversalStrategy` instances in GraphBinary.
* Fixed bug in bytecode `Bindings` where calling `of()` prior to calling a child traversal in the same parent would cause the initial binding to be lost.
* Migrated from Tornado to AIOHTTP for gremlinpython.
* Bumped to Neo4j 3.4.11.
* Bumped to Spark 3.0.0.
* Bumped to Jackson 2.11.x.
* Supported build for Java 11.
* Added `MessageSerializer.getMapper()` to return the underlying object that handles serialization for a particular implementation.
* Added a parameterized `TypeTranslator` for use with `GroovyTranslator` that should produce more cache hits.
* Added support for `TextP` in Neo4j using its string search functions.
* Added a kerberos KDC to the docker container for testing GLV's.
* Added kerberos authentication to Gremlin-Python.
* Added audit logging to bytecode-based traversals.
* Changed `TraversalStrategy` application methodology to apply each strategy in turn to each level of the traversal hierarchy starting from root down to children.
* Added a VertexProgramRestrictionStrategy.
* Prevented more than one `Client` from connecting to the same Gremlin Server session.
* Changed the Groovy to an optional dependency in `gremlin-driver`.
* Added support for configuring an `Authorizer` implementation to Gremlin Server, allowing for authorization of individual gremlin requests.
* Added `gremlint` module to house the Gremlin query formatting JavaScript library powering gremlint.com.
* Removed internal functionality for the session close message in Gremlin Server - the message is accepted but ignored if sent.
* Removed `Property.Exceptions.propertyValueCanNotBeNull` exception type as `null` now has meaning in Gremlin.
* Removed the "experimental" support for multi/meta-properties in Neo4j.
* Removed Gryo serialization configurations from Gremlin Server sample configurations and default configurations.
* Removed previously deprecated custom keep-alive functionality in the Java driver.
* Removed previously deprecated `BytecodeUtil`.
* Removed previously deprecated `Cluster.maxWaitForSessionClose` configuration option.
* Removed previously deprecated `TraversalStrategies.applyStrategies()`.
* Removed previously deprecated `scriptEvaluationTimeout`.
* Removed previously deprecated `NioChannelizer` and related classes.
* Removed previously deprecated remote traversal side-effects and related infrastructure.
* Removed previously deprecated `Serializers.DEFAULT_RESULT_SERIALIZER` and `Serializers.DEFAULT_REQUEST_SERIALIZER`.
* Removed previously deprecated `decr` and `incr` from `Order`.
* Removed previously deprecated `TraversalSource.withRemote()`.
* Removed previously deprecated `ResponseHandlerContext` infrastructure.
* Removed previously deprecated `VertexProgram` related infrastructure.
* Removed previously deprecated SSL settings: `keyCertChainFile`, `keyFile`, `keyPassword` and `trustCertChainFile` and related infrastructure.
* Removed previously deprecated `PropertyMapStep` constructor and `isIncludeTokens`.
* Removed previously deprecated `StarGraph.builder()` and `StarGraph.Builder.create()`.
* Removed previously deprecated `AbstractOpProcessor.generateMetaData(ChannelHandlerContext, RequestMessage, ResponseStatusCode, Iterator)`
* Removed previously deprecated `BulkDumperVertexProgram` and `BulkLoaderVertexProgram`.

==== Bugs

* TINKERPOP-1619 TinkerGraphComputer worker count affects OptionalStep query results
* TINKERPOP-2107 Spark fails to reattach properties
* TINKERPOP-2157 SparkStarBarrierInterceptor injects (Byte) 0
* TINKERPOP-2159 EventStrategy doesn't handle multi-valued properties
* TINKERPOP-2175 Executor thread is not returned on channel close
* TINKERPOP-2185 Use commons-configuration2 instead of commons-configuration *(breaking)*
* TINKERPOP-2192 Gremlin.Net.Driver.Connection.Parse throws a NullReferenceException
* TINKERPOP-2224 Detect and fix resource leak
* TINKERPOP-2230 match() step unexpected behaviours
* TINKERPOP-2232 RemoteStrategy does not call parent class TraversalStrategy __init__
* TINKERPOP-2238 Fix remaining iterator leaks marked by @IgnoreIteratorLeak
* TINKERPOP-2241 Client exception don't match Server exception when server  throw StackOverflowError
* TINKERPOP-2248 Instability of driver for blocked requests
* TINKERPOP-2257 transaction itty  may still be visited after commit
* TINKERPOP-2264 Gremlin Python should deserialize g:Date to UTC
* TINKERPOP-2266 Keep alive not started at connection creation
* TINKERPOP-2274 Test of TinkerGraph Gremlin fail on Windows and non EN locale
* TINKERPOP-2276 No constructor for remote connection in DSL generated traversal source
* TINKERPOP-2283 GraphStep's ids null exception
* TINKERPOP-2285 Error object is unreachable
* TINKERPOP-2288 Get ConnectionPoolBusyException and then ServerUnavailableExceptions
* TINKERPOP-2289 Use address instead of hostname for connection
* TINKERPOP-2290 Javascript GLV connection refused error handling
* TINKERPOP-2291 TraversalExplanation deserialization in GraphSON
* TINKERPOP-2298 Bytecode.java  flattenArguments throw exception when null
* TINKERPOP-2303 GremlinDsl generate addV instead of addE
* TINKERPOP-2318 Edge properties dedup() not work with spark-gremlin *(breaking)*
* TINKERPOP-2337 In upgrade guide for 3.4.2, the option RemoteConnection.PER_REQUEST_TIMEOUT does not exist
* TINKERPOP-2338 drop() not removing all edge/meta properties
* TINKERPOP-2341 GremlinClientExtensions.SubmitAsync hangs as it tries to dispose connection
* TINKERPOP-2345 NullPointerException when Map key is not found for math()
* TINKERPOP-2347 Remove invalid service descriptors from gremlin-shaded
* TINKERPOP-2350 clone() is not deep copying Traversal internals
* TINKERPOP-2351 Local Map ordering of keys can generate cast errors
* TINKERPOP-2352 Gremlin Python driver default pool size makes Gremlin keep-alive difficult
* TINKERPOP-2353 Error while Shutting Down Gremlin Server
* TINKERPOP-2360 failed to deserializer int32 when gremlin-python submit bytecode with a big int value
* TINKERPOP-2364 Injected ProfileStep should not be displayed in child traversals
* TINKERPOP-2365 LazyBarrierStrategy adds a NoOpBarrierStep when profile() is present
* TINKERPOP-2368 JAVA_OPTIONS are not properly expanded in gremlin-console
* TINKERPOP-2369 Connections in ConnectionPool are not replaced in background when underlying channel is closed
* TINKERPOP-2374 SaslAndHttpBasicAuthenticationHandler can't extract authorization
* TINKERPOP-2383 has(T,Traversal) does not return results
* TINKERPOP-2384 Inject and withSideEffect causing different outcomes in order step
* TINKERPOP-2388 gremlinpython: Can't close DriverRemoteConnection
* TINKERPOP-2403 Gremlin javascript Translator does not handle child traversals
* TINKERPOP-2405 gremlinpython: traversal hangs when the connection is established but the servers stops responding later
* TINKERPOP-2408 Iterator leak in HasContainer
* TINKERPOP-2409 js: DriverRemoteConnection never times out if server uri not available.
* TINKERPOP-2410 Free up server threads when client is closed
* TINKERPOP-2425 Server closes HTTP connection for keepAlive as true
* TINKERPOP-2432 Generate correct toString() representation of bytecode in Javascript
* TINKERPOP-2433 typo in javadocs match() Type Parameters
* TINKERPOP-2435 Gremlin Python sugar syntax for values() can lead to unexpected problems
* TINKERPOP-2437 gremlin-driver hangs if ResultSet.statusAttributes().get() is called when the request throws
* TINKERPOP-2439 P and TextP toString() is broken
* TINKERPOP-2458 Bytecode Bindings lost when followed by a child traversal
* TINKERPOP-2465 TestHelper.generateTempFileFromResource file handling is invalid on windows
* TINKERPOP-2475 Barrier step touches one more element of next loop
* TINKERPOP-2478 Console byte code translator has issues with "new Date()"
* TINKERPOP-2496 GremlinDslProcessor fails when SocialTraversalSourceDsl overrides close
* TINKERPOP-2505 Gremlin Python Client Query Times out at 30 seconds instead of the server timeout
* TINKERPOP-2512 Duplicate jars in classpath when running gremlin-server.sh
* TINKERPOP-2513 Generics insufficiently strict on property()
* TINKERPOP-2514 Java client driver requests with same request ids hang
* TINKERPOP-2516 Property folding has trouble with coalesce
* TINKERPOP-2529 Global dedup() in reducing by() of group() detaches elements for OLTP
* TINKERPOP-2531 Gremlin .NET driver ConnectionPool can remain without connections if server is down for 1-2 minutes

==== Improvements

* TINKERPOP-709 Consider Bounding Gremlin Pool Queue Size
* TINKERPOP-1084 Branch option tokens should be allowed to be traversals.
* TINKERPOP-1553 Deprecate store() in favor of aggregate(Scope)
* TINKERPOP-1568 Change strategy application order *(breaking)*
* TINKERPOP-1641 Kerberos authentication for gremlin-python
* TINKERPOP-1682 by-modulator optimization strategy
* TINKERPOP-1733 hasKey, hasValues should work on Element and Property
* TINKERPOP-1810 Add Lambda.binaryOperator and Lambda.unaryOperator
* TINKERPOP-1838 Python sample script
* TINKERPOP-1886 Gremlin Python driver to periodically issue ping / heartbeat to gremlin server
* TINKERPOP-1921 Support hasNext terminal step in GLVs
* TINKERPOP-1994 LazyBarrierStrategy fully responsible for barrier() additions
* TINKERPOP-2001 Support lambdas in Javascript
* TINKERPOP-2014 Allow an ability to specify seeding for random methods such as coin, sample and Order.shuffle
* TINKERPOP-2020 Support withComputer() for javascript
* TINKERPOP-2046 Gremlin-Python: Support custom request headers in WebSocket request
* TINKERPOP-2054 Support TraversalStrategy specification in gremlin-javascript
* TINKERPOP-2076 Build with Java 11
* TINKERPOP-2080 Remove deprecated TraversalSource.withRemote() *(breaking)*
* TINKERPOP-2099 Property setting with null has different behavior between add and update *(breaking)*
* TINKERPOP-2133 Use neo4j index lookup in Neo4jGraphStep with HasContainers containing TextP predicates
* TINKERPOP-2168 GraphSON: P deserialization should be optimized
* TINKERPOP-2213 Replace scriptEvaluationTimeout in favor of something more suitable to bytecode
* TINKERPOP-2215 Better exception message for connection problems
* TINKERPOP-2223 Update jackson databind to 2.9.9
* TINKERPOP-2231 Remove deprecated bulk dumping/loading VertexPrograms *(breaking)*
* TINKERPOP-2233 Remove deprecated Order decr/incr *(breaking)*
* TINKERPOP-2235 Better handle the concept of null in traversals *(breaking)*
* TINKERPOP-2236 Improve error messaging for TinkerGraph IdManagers that fail on conversions
* TINKERPOP-2237 Prevent error when closing sessions that don't exist *(breaking)*
* TINKERPOP-2239 Remove previously deprecated SSL configuration options *(breaking)*
* TINKERPOP-2242 Bump to netty 4.1.36
* TINKERPOP-2243 Add user-agent to RequestOptions
* TINKERPOP-2245 Consolidate the executor for bytecode & string based client
* TINKERPOP-2246 Consolidate the error propagation to the client
* TINKERPOP-2250 Support toString serialization in GraphBinary
* TINKERPOP-2251 Remove deprecated VertexProgram-related methods *(breaking)*
* TINKERPOP-2252 A meaningful way to support session based byteCode interaction through gremlin-driver
* TINKERPOP-2254 Rename AggregateStep and StoreStep given aggregate(Scope,String) *(breaking)*
* TINKERPOP-2256 processAllStarts of AggregateStep should only be called when barrier is empty
* TINKERPOP-2259 Default Java based driver and server operations to GraphBinary and remove Gryo *(breaking)*
* TINKERPOP-2260 Update jackson databind 2.9.9.1
* TINKERPOP-2262 Improve Netty protocol handling
* TINKERPOP-2265 Deprecate Traversal.getSideEffects() functionality for remoting purposes
* TINKERPOP-2269 Remove remote side-effect related infrastructure *(breaking)*
* TINKERPOP-2270 Deprecate multi/metaproperty support in Neo4j
* TINKERPOP-2271 Add console preference to control server-originated warning display
* TINKERPOP-2272 Rename steps and tokens that conflict with standard python functions
* TINKERPOP-2273 Remove deprecated ResponseHandlerContext infrastructure *(breaking)*
* TINKERPOP-2277 Python sdk postpone the timing to create transport
* TINKERPOP-2279 GraphBinary support in Python
* TINKERPOP-2280 Prevent use of T values as property key overloads
* TINKERPOP-2284 Make it easier to return more structure of graph elements
* TINKERPOP-2295 Remove deprecated scriptEvaluationTimeout *(breaking)*
* TINKERPOP-2296 Per query timeout not working from Python
* TINKERPOP-2302 Add isOnGraphComputer() field accessor to ElementMapStep
* TINKERPOP-2307 Add better error message for badly configured Channelizer
* TINKERPOP-2310 Reduce Traversal.isRoot() to a check of EmptyStep *(breaking)*
* TINKERPOP-2311 TraversalStrategies implementing Iterable *(breaking)*
* TINKERPOP-2312 Empty keys to group() should group to null
* TINKERPOP-2314 Employ by(String) for Map when possible and improve errors around incorrect types
* TINKERPOP-2315 Implement some form of clone() or reset() for Traversal in GLVs
* TINKERPOP-2317 Remove Python 2 support *(breaking)*
* TINKERPOP-2320 [SECURITY] XMLInputFactory initialization in GraphMLReader introduces
* TINKERPOP-2325 Generate traversals that will better yield index lookups with SPARQL
* TINKERPOP-2327 Remove deprecated NIO protocol support *(breaking)*
* TINKERPOP-2328 Do not close all connections if just one has became closed
* TINKERPOP-2335 Drop support for older GLV runtimes
* TINKERPOP-2336 Allow close of channel without having to wait for server
* TINKERPOP-2349 Switch from Newtonsoft.Json to System.Text.Json *(breaking)*
* TINKERPOP-2354 Document recommendation to reuse graph traversal source
* TINKERPOP-2356 Bump to Jackson 2.10.x
* TINKERPOP-2357 Add a command to clear the Gremlin Console screen
* TINKERPOP-2361 Prevent using GraphTraversalSource spawned traversals as children *(breaking)*
* TINKERPOP-2371 Add possibility to import constants with ImportGremlinPlugin
* TINKERPOP-2376 Probability distribution controlled by weight when using sample step
* TINKERPOP-2377 Investigate intermittent .NET GLV test failures
* TINKERPOP-2389 Authorization support in TinkerPop
* TINKERPOP-2391 Drop GLV Templating System
* TINKERPOP-2392 Improve module level documentation for GLVs
* TINKERPOP-2394 Unable to use __ class of a custom DSL when passing a script even if this class is imported *(breaking)*
* TINKERPOP-2395 Gremlin Python doesn't support list as keys in groupCount
* TINKERPOP-2396 TraverserSet should be extendable for GraphDB provider
* TINKERPOP-2397 Don't create the default Gyro serializer if the caller specifies a different one
* TINKERPOP-2401 Upgrade Jackson-databind to 2.11.x
* TINKERPOP-2406 Delegate processing from event loop to worker threads
* TINKERPOP-2407 Support deserialization of a dict that has a dict as a key
* TINKERPOP-2412 Add missing query tests
* TINKERPOP-2413 Prefer withEmbedded() to withGraph() on AnonymousTraversalSource
* TINKERPOP-2415 Avoid unnecessary detached objects if not required
* TINKERPOP-2416 MultiIterator should implement AutoCloseable
* TINKERPOP-2418 Store authenticated user on server pipeline
* TINKERPOP-2420 Support per query request options in .NET
* TINKERPOP-2421 Support per query options in javascript
* TINKERPOP-2426 Use Netty's WebSocketClientProtocolHandler
* TINKERPOP-2427 Simplify Netty reference counting
* TINKERPOP-2430 Looping Recipies
* TINKERPOP-2431 Operating on Dropped Elements Recipes
* TINKERPOP-2436 The gremlin server starts even if all graphs instantiation has failed
* TINKERPOP-2438 Provide a way for scripts to respect with() specification of timeout
* TINKERPOP-2440 Simplify driver by delegating keepAlive logic to Netty
* TINKERPOP-2441 Add compression to WebSocket frames sent from client
* TINKERPOP-2442 Make Translators that work in Java part of gremlin-core
* TINKERPOP-2443 Improve testing of Translator instances for non-JVM languages with focus on Python as a model
* TINKERPOP-2445 Speed up client initialization *(breaking)*
* TINKERPOP-2446 Add Recipe for Optional Looping
* TINKERPOP-2447 Improve handling of StackOverflowError for long traversals
* TINKERPOP-2451 JavascriptTranslator for Java
* TINKERPOP-2452 DotNetTranslator for Java
* TINKERPOP-2453 Add WebSocket compression to gremlin-python
* TINKERPOP-2455 Remove deprecated custom keep-alive functionality in the Java driver Channelizer *(breaking)*
* TINKERPOP-2457 Add a max_content_length parameter to DriverRemoteConnection in the Python client
* TINKERPOP-2460 Change groovy to provided scope in gremlin-driver *(breaking)*
* TINKERPOP-2461 Align CoreImports with GroovyTranslator
* TINKERPOP-2462 Duplicated BytecodeUtil and BytecodeHelper classes
* TINKERPOP-2466 Improve syntax for Groovy scripts that use withStrategies()
* TINKERPOP-2468 Stabilize shouldProcessSessionRequestsInOrder() test
* TINKERPOP-2469 KrbException - Principal does not exist in test
* TINKERPOP-2470 Bump gremlinpython to tornado 6.x
* TINKERPOP-2472 GraphBinary support in .NET
* TINKERPOP-2473 Prevent TraversalStrategy instances of the same type to be added to a TraversalSource
* TINKERPOP-2474 withSack() Groovy translation output could be simplified
* TINKERPOP-2476 Provide fully shaded version of Java driver
* TINKERPOP-2479 Provide a way to set a custom GraphSONMapper for :bytecode command
* TINKERPOP-2481 IdentityRemovalStrategy not installed *(breaking)*
* TINKERPOP-2482 Rename wsConnectionTimeout to connectionSetupTimeout
* TINKERPOP-2484 Python  IOLoop close errors
* TINKERPOP-2485 Invalid http tests with ?gremlin=1-1
* TINKERPOP-2494 Document Translator parameter extraction functionality
* TINKERPOP-2499 PathRetractionStrategy returns inconsistent results when match() is not detected as the final step *(breaking)*
* TINKERPOP-2500 Add none() step for all GLVs
* TINKERPOP-2506 Expose client WebSocket connection status
* TINKERPOP-2517 Introduce a retry status code to the server protocol
* TINKERPOP-2527 Add a GroovyTranslator equivalent method to the Python client
* TINKERPOP-2530 Transfer OyvindSabo/gremlint and OyvindSabo/gremlint.com to apache/tinkerpop/gremlint
* TINKERPOP-2532 MaxBarrierSize of NoOpBarrierStep should be accessible
* TINKERPOP-2533 Develop a grammar for Gremlin
* TINKERPOP-2535 Netty 4.1.52 flagged as medium security violation
* TINKERPOP-2537 Support bytecode based requests in sessions and remote tx()
* TINKERPOP-2544 Modify site publishing scripts to include gremlint
* TINKERPOP-2546 Change transport layer to use AIOHTTP instead of Tornado
* TINKERPOP-2547 Provide an option to supply a callback before handshake submission
* TINKERPOP-2550 Deadlock on Client initialization

== TinkerPop 3.4.0 (Avant-Gremlin Construction #3 for Theremin and Flowers)

image::https://raw.githubusercontent.com/apache/tinkerpop/master/docs/static/images/avant-gremlin.png[width=185]

[[release-3-4-13]]
=== TinkerPop 3.4.13 (Release Date: January 10, 2022)

* Fixed `RangeGlobalStep` which was prematurely closing the iterator.
* Added explicit state to `DefaultTraversal` to track whether or not it was fully iterated and closed to ensure it released resources properly.
* Prevented XML External Entity (XXE) style attacks via `GraphMLReader` by disabling DTD and external entities by default.
* Improved error message for failed serialization for HTTP-based requests.
* Fixed a `NullPointerException` that could occur during a failed `Connection` initialization due to uninstantiated `AtomicInteger`.
* Minor changes to the initialization of Java driver `Cluster` and `Client` such that hosts are marked as available only after successfully initializing connection pools.
* `NoHostAvailableException` now contains a cause for the failure.
* Bumped to Netty 4.1.72.
* Added user-friendly message in Gremlin console for unavailable hosts upon initiation and fixed possible leak in `RemoteCommand.groovy` upon `RemoteException`.

==== Bugs

* TINKERPOP-2569 Reconnect to server if Java driver fails to initialize
* TINKERPOP-2589 XML External Entity (XXE) vulnerability
* TINKERPOP-2597 NullPointerException while initializing connection pool
* TINKERPOP-2603 TinkerGraph sometimes could not query float values.
* TINKERPOP-2609 HTTP returns serialization exceptions for the GraphTraversalSource
* TINKERPOP-2626 RangeGlobalStep closes traversal prematurely

==== Improvements

* TINKERPOP-2504 Intermittently failing server/driver integration tests
* TINKERPOP-2616 Provide better exceptions with SSL related failures *(breaking)*
* TINKERPOP-2630 Clarify that a server cannot support Graphson1.0 over HTTP
* TINKERPOP-2632 Netty 4.1.61 flagged with two high severity security violations
* TINKERPOP-2669 Netty 4.1.61 flagged with medium severity security violations

[[release-3-4-12]]
=== TinkerPop 3.4.12 (Release Date: July 19, 2021)

* Coerced single `set` arguments to `P.within` and `P.without` to `list` in Python which serializes to a more expected form for `P` instances.
* Fixed bug in the `vertexLabelKey` validation for `GraphMLWriter` which was inadvertently validating the `edgeLabelKey`.
* Changed `IndexStep` to make it easier for providers to determine the type of indexer being used.
* Allowed Javascript `Translator` to take `Bytecode` or a `Traversal`.
* Addressed CVE-2021-32640 for gremlin-javascript.
* Allowed construction of `DriverRemoteConnection` in .NET to use host and port specification similar to Java syntax.
* Defaulted `DriverRemoteConnection` to "g" if it the `TraversalSource` binding isn't supplied in Python.
* Initialized metrics in `ProfileStep` even if the step hasn't iterated.

==== Bugs

* TINKERPOP-2358 Potential connection leak on client disposing
* TINKERPOP-2554 Extracting step metrics from ProfileStep throws NPE if the step was not triggered
* TINKERPOP-2565 GraphMLWriter does not check vertexLabelKey conflict
* TINKERPOP-2578 Set arguments to P within/without are wrapped in List
* TINKERPOP-2580 Update the custom DSL documentation

==== Improvements

* TINKERPOP-2548 Add getter for indexer used in IndexStep
* TINKERPOP-2577 Remove unused test coverage dependencies from Gremlin.NET

[[release-3-4-11]]
=== TinkerPop 3.4.11 (Release Date: May 3, 2021)

* Prevented Java driver from sending multiple request messages with the same identifier.
* Improved error message for `property(T,Object)` when mutating graph elements.
* Added method caching for GraphSON 3.0 deserialization of `P` and `TextP` instances.
* Allowed setting `ssl_options` for gremlin-python.  
* Fixed bug with global `dedup()` when used in reducing `by()` of `group()`.
* Fixed bug with Javascript Groovy `Translator` when generating Gremlin with multiple embedded traversals.
* Modified Gremlin Server `Settings` to be more extensible allowing for custom options with the YAML parser.
* Fixed `toString()` representation of `P` when string values are present in Javascript.
* Exposed barrier size with getter for `NoOpBarrierStep`.
* Bumped to Netty 4.1.61.
* Added `max_content_length` as a Python driver setting.
* Fixed bug in Java `Client` initialization, reconnect and shutdown where certain thread pool configurations might produce a deadlock.
* Ensured that `barrier()` additions by strategies were controlled solely by `LazyBarrierStrategy`.
* Fixed `NullPointerException` in `ResponseMessage` deserialization for GraphSON.
* Enabled the Gremlin.Net driver to repair its connection pool after the server was temporarily unavailable.
* Added the ability to supply a `HandshakeInterceptor` to a `Cluster` which will provide access to the initial HTTP request that establishes the websocket.
* Fixed a possible leakage of connections in the Gremlin.NET driver that could happen if `Dispose()` was called while the pool was creating connections.

==== Bugs

* TINKERPOP-2512 Duplicate jars in classpath when running gremlin-server.sh
* TINKERPOP-2514 Java client driver requests with same request ids hang
* TINKERPOP-2516 Property folding has trouble with coalesce
* TINKERPOP-2529 Global dedup() in reducing by() of group() detaches elements for OLTP
* TINKERPOP-2531 Gremlin .NET driver ConnectionPool can remain without connections if server is down for 1-2 minutes

==== Improvements

* TINKERPOP-1994 LazyBarrierStrategy fully responsible for barrier() additions
* TINKERPOP-2168 GraphSON: P deserialization should be optimized
* TINKERPOP-2457 Add a max_content_length parameter to DriverRemoteConnection in the Python client
* TINKERPOP-2532 MaxBarrierSize of NoOpBarrierStep should be accessible
* TINKERPOP-2535 Netty 4.1.52 flagged as medium security violation
* TINKERPOP-2547 Provide an option to supply a callback before handshake submission
* TINKERPOP-2550 Deadlock on Client initialization

[[release-3-4-10]]
=== TinkerPop 3.4.10 (Release Date: January 18, 2021)

* Added `GremlinScriptChecker` to provide a way to extract properties of scripts before doing an actual `eval()`.
* Added `none()` step for all language variants.
* Fixed bug in `PythonTranslator` which was improperly translating `Lambda` scripts.
* Fixed bug in `GremlinDslProcessor` where certain return types in `TraversalSource` definitions were not generating code that would compile.
* Changed the default read and write timeout values for the `TornadoTransport` to `None` to disable it.
* Bumped to Groovy 2.5.14.

==== Bugs

* TINKERPOP-2496 GremlinDslProcessor fails when SocialTraversalSourceDsl overrides close
* TINKERPOP-2505 Gremlin Python Client Query Times out at 30 seconds instead of the server timeout

==== Improvements

* TINKERPOP-2447 Improve handling of StackOverflowError for long traversals
* TINKERPOP-2485 Invalid http tests with ?gremlin=1-1
* TINKERPOP-2500 Add none() step for all GLVs

[[release-3-4-9]]
=== TinkerPop 3.4.9 (Release Date: December 7, 2020)

* Modified the text of `profile()` output to hide step instances injected for purpose of collecting metrics.
* Bumped to Jackson 2.11.x.
* Bumped Netty 4.1.52.
* Added lambda support for `gremlin-javascript`.
* Provided a more concise syntax for constructing strategies in Groovy.
* Aligned `CoreImports` with `GroovyTranslator` to generate more succinct syntax.
* Improved `gremlin-groovy` understanding of `withSack()` overloads to avoid forced casts.
* Moved `Translator` instances to `gremlin-core`.
* Prevented barriers from over-reaching their limits by one.
* Added `CheckedGraphManager` to prevent Gremlin Server from starting if there are no graphs configured.
* Fixed bug in bytecode `Bindings` where calling `of()` prior to calling a child traversal in the same parent would cause the initial binding to be lost.
* Established a default read and write timeout for the `TornadoTransport` in Python, allowing it to be configurable.
* Delegated handling of erroneous response to the worker thread pool instead of event loop thread pool in Java Driver.
* Removed `Connection` from `Connection Pool` when server closes a connection with no pending requests in Java Driver.
* Improved initialization time of Java Driver if the default serializer is replaced.
* Deprecated `withGraph()` in favor of `withEmbedded()` on `AnonymousTraversalSource`.
* Added support for per-request level configurations, like timeouts, in .NET, Python and Javascript.
* Fixed bug in Javascript `Translator` that wasn't handling child traversals well.
* Prevented Gremlin Python sugar from being confused by Python magic methods.
* Allowed Gremlin Python sugar calls from anonymous context.
* Implemented `AutoCloseable` on `MultiIterator`.
* Fixed an iterator leak in `HasContainer`.
* Fixed bug in `:bytecode` command preventing translations with whitespace from working properly.
* Added `reset` and `config` options to the `:bytecode` command to allow for greater customization options.
* Added GraphSON extension module and the `TinkerIoRegistry` to the default `GraphSONMapper` configuration used by the `:bytecode` command.
* Added `GremlinASTChecker` to provide a way to extract properties of scripts before doing an actual `eval()`.
* Avoided creating unnecessary detached objects in JVM.
* Added support for `TraversalStrategy` usage in Javascript.
* Added `Traversal.getTraverserSetSupplier()` to allow providers to supply their own `TraverserSet` instances.
* Release server threads waiting on connection if the connection is dead.
* Fixed bug where server closes HTTP connection on request error even if keep alive is set to true.
* Deprecated driver `Channelizer` keep-alive related methods.
* Delegate handling of WebSocket handshake to Netty instead of custom code in Java Driver.
* Delegate detection of idle connection to Netty instead of custom keep alive logic for `WebSocketChannelizer`.
* Added support for WebSocket frame compression extension ( [RFC7692](https://tools.ietf.org/html/rfc7692) ) for `WebSocketChannelizer` in Java/Python driver.
* Added server support for WebSocket compression extension ( [RFC7692](https://tools.ietf.org/html/rfc7692) ).
* Fixed bug with Bytecode serialization when `Bytecode.toString()` is used in Javascript.
* Fixed "toString" for P and TextP to produce valid script representation from bytecode glv steps containing a string predicate in Javascript.
* Fixed a bug which could cause Java driver to hang when using `ResultSet.statusAttributes()`
* Added a listener to javascript's `DriverRemoteConnection` to find note errors from websocket connection setup.
* Fixed bug with `ReservedVerificationStrategy.getConfiguration()` which was omitting the reserved `keys` value.
* Changed all configuration keys on `AbstractWarningVerificationStrategy` implementations to `public`.
* Deprecated `BytecodeUtil` and merged its functionality to the existing `BytecodeHelper`.
* Added configuring implementation in HasStep
* Remove static initialization for `GraphSONMessageSerializerV1d0` and `GraphSONMessageSerializerV1d0` in Java driver.
* Connections to the server in a connection pool are created in parallel instead of serially in Java Driver.
* Connection pools for multiple endpoints are created in parallel instead of serially in Java Driver.
* Introduced new HostNotAvailable exception to represent cases when no server with active connection is available.
* Don't wait for new requests during shutdown of event loop group in Java Driver.

==== Bugs

* TINKERPOP-2364 Injected ProfileStep should not be displayed in child traversals
* TINKERPOP-2369 Connections in ConnectionPool are not replaced in background when underlying channel is closed
* TINKERPOP-2403 Gremlin javascript Translator does not handle child traversals
* TINKERPOP-2405 gremlinpython: traversal hangs when the connection is established but the servers stops responding later
* TINKERPOP-2408 Iterator leak in HasContainer
* TINKERPOP-2409 js: DriverRemoteConnection never times out if server uri not available.
* TINKERPOP-2410 Free up server threads when client is closed
* TINKERPOP-2425 Server closes HTTP connection for keepAlive as true
* TINKERPOP-2432 Generate correct toString() representation of bytecode in Javascript
* TINKERPOP-2433 typo in javadocs match() Type Parameters
* TINKERPOP-2435 Gremlin Python sugar syntax for values() can lead to unexpected problems
* TINKERPOP-2437 gremlin-driver hangs if ResultSet.statusAttributes().get() is called when the request throws
* TINKERPOP-2439 P and TextP toString() is broken
* TINKERPOP-2458 Bytecode Bindings lost when followed by a child traversal
* TINKERPOP-2465 TestHelper.generateTempFileFromResource file handling is invalid on windows
* TINKERPOP-2475 Barrier step touches one more element of next loop
* TINKERPOP-2478 Console byte code translator has issues with "new Date()"

==== Improvements

* TINKERPOP-2001 Support lambdas in Javascript
* TINKERPOP-2054 Support TraversalStrategy specification in gremlin-javascript
* TINKERPOP-2296 Per query timeout not working from Python
* TINKERPOP-2392 Improve module level documentation for GLVs
* TINKERPOP-2396 TraverserSet should be extendable for GraphDB provider
* TINKERPOP-2397 Don't create the default Gyro serializer if the caller specifies a different one
* TINKERPOP-2401 Upgrade Jackson-databind to 2.11.x
* TINKERPOP-2406 Delegate processing from event loop to worker threads
* TINKERPOP-2412 Add missing query tests
* TINKERPOP-2413 Prefer withEmbedded() to withGraph() on AnonymousTraversalSource
* TINKERPOP-2415 Avoid unnecessary detached objects if not required
* TINKERPOP-2416 MultiIterator should implement AutoCloseable
* TINKERPOP-2420 Support per query request options in .NET
* TINKERPOP-2421 Support per query options in javascript
* TINKERPOP-2426 Use Netty's WebSocketClientProtocolHandler
* TINKERPOP-2427 Simplify Netty reference counting
* TINKERPOP-2430 Looping Recipies
* TINKERPOP-2431 Operating on Dropped Elements Recipes
* TINKERPOP-2436 The gremlin server starts even if all graphs instantiation has failed
* TINKERPOP-2438 Provide a way for scripts to respect with() specification of timeout
* TINKERPOP-2440 Simplify driver by delegating keepAlive logic to Netty
* TINKERPOP-2441 Add compression to WebSocket frames sent from client
* TINKERPOP-2442 Make Translators that work in Java part of gremlin-core
* TINKERPOP-2445 Speed up client initialization *(breaking)*
* TINKERPOP-2446 Add Recipe for Optional Looping
* TINKERPOP-2453 Add WebSocket compression to gremlin-python
* TINKERPOP-2461 Align CoreImports with GroovyTranslator
* TINKERPOP-2462 Duplicated BytecodeUtil and BytecodeHelper classes
* TINKERPOP-2466 Improve syntax for Groovy scripts that use withStrategies()
* TINKERPOP-2468 Stabilize shouldProcessSessionRequestsInOrder() test
* TINKERPOP-2469 KrbException - Principal does not exist in test
* TINKERPOP-2474 withSack() Groovy translation output could be simplified
* TINKERPOP-2479 Provide a way to set a custom GraphSONMapper for :bytecode command
* TINKERPOP-2482 Rename wsConnectionTimeout to connectionSetupTimeout

[[release-3-4-8]]
=== TinkerPop 3.4.8 (Release Date: August 3, 2020)

* Fixed bug in `has(T,Traversal)` where results were not being returned.
* Fixed bug in `select(Traversal)` where side-effects were getting lost if accessed from the child traversal.
* Fixed authorization bug when using `WsAndHttpChannelizerHandler` with keep-alive enabled.
* Fixed bug in option-less construction of `DriverRemoteConnection` in Javascript.
* Bumped Jackson to 2.9.10.5.
* Improved sampling distribution for global scope `sample()` operations.

==== Bugs

* TINKERPOP-2288 Get ConnectionPoolBusyException and then ServerUnavailableExceptions
* TINKERPOP-2352 Gremlin Python driver default pool size makes Gremlin keep-alive difficult
* TINKERPOP-2374 SaslAndHttpBasicAuthenticationHandler can't extract authorization
* TINKERPOP-2383 has(T,Traversal) does not return results
* TINKERPOP-2384 Inject and withSideEffect causing different outcomes in order step

==== Improvements

* TINKERPOP-2328 Do not close all connections if just one has became closed
* TINKERPOP-2376 Probability distribution controlled by weight when using sample step

[[release-3-4-7]]
=== TinkerPop 3.4.7 (Release Date: June 1, 2020)

This release also includes changes from <<release-3-3-11, 3.3.11>>.

* Gremlin.NET driver: Fixed a `NullReferenceException` and throw clear exception if received message is empty.
* Bumped to Groovy 2.5.11.
* Modified `ImportGremlinPlugin` to allow for field imports.
* Improved error message for `math()` when the selected key in a `Map` is `null` or not a `Number`.
* Added `:cls` command to Gremlin Console to clear the screen.
* Bumped Netty 4.1.49.

==== Bugs

* TINKERPOP-2192 Gremlin.Net.Driver.Connection.Parse throws a NullReferenceException
* TINKERPOP-2345 NullPointerException when Map key is not found for math()
* TINKERPOP-2347 Remove invalid service descriptors from gremlin-shaded
* TINKERPOP-2350 clone() is not deep copying Traversal internals
* TINKERPOP-2351 Local Map ordering of keys can generate cast errors
* TINKERPOP-2353 Error while Shutting Down Gremlin Server
* TINKERPOP-2355 Jackson-databind version in Gremlin shaded dependency needs to be increased  - introduces vulnerability issues
* TINKERPOP-2360 failed to deserializer int32 when gremlin-python submit bytecode with a big int value
* TINKERPOP-2365 LazyBarrierStrategy adds a NoOpBarrierStep when profile() is present
* TINKERPOP-2368 JAVA_OPTIONS are not properly expanded in gremlin-console

==== Improvements

* TINKERPOP-2215 Better exception message for connection problems
* TINKERPOP-2336 Allow close of channel without having to wait for server
* TINKERPOP-2339 Gremlin.Net: Update System.Net.WebSockets.Client dependency
* TINKERPOP-2354 Document recommendation to reuse graph traversal source
* TINKERPOP-2357 Add a command to clear the Gremlin Console screen
* TINKERPOP-2371 Add possibility to import constants with ImportGremlinPlugin

[[release-3-4-6]]
=== TinkerPop 3.4.6 (Release Date: February 20, 2020)

* Fixed bug in `drop()` of properties which was introduced in 3.4.5.

==== Bugs

* TINKERPOP-2338 drop() not removing all edge/meta properties

[[release-3-4-5]]
=== TinkerPop 3.4.5 (Release Date: February 3, 2020)

This release also includes changes from <<release-3-3-10, 3.3.10>>.

* Expanded the use of `by(String)` modulator so that it can work on `Map` as well as `Element`.
* Improved error messaging for `by(String)` so that it is more clear as to what the problem is
* Bumped to Netty 4.1.42
* Improved SPARQL query translation to better allow for index optimizations during execution.
* Improved Gremlin Server websocket handling preventing automatic server close of the channel for protocol errors.
* Introduced internal `Buffer` API as a way to wrap Netty's Buffer API and moved `GraphBinaryReader`, `GraphBinaryWriter` and `TypeSerializer<T>` to `gremlin-core`.
* Unified the behavior of property comparison: only compare key&value.
* Supported `hasKey()` and `hasValue()` step for edge property and meta property, like `g.E().properties().hasKey('xx')`.
* Modified driver to send `overrideRequestId` and `userAgent` to server when they are present in `RequestOptions` for bytecode requests.

==== Bugs

* TINKERPOP-2175 Executor thread is not returned on channel close
* TINKERPOP-2266 Keep alive not started at connection creation
* TINKERPOP-2274 Test of TinkerGraph Gremlin fail on Windows and non EN locale
* TINKERPOP-2318 Edge properties dedup() not work with spark-gremlin *(breaking)*
* TINKERPOP-2332 JavaScript GLV: structure element toString() should internally call toString()
* TINKERPOP-2333 JavaScript GLV: GraphSON2/3 Edge deserialization is invalid

==== Improvements

* TINKERPOP-1733 hasKey, hasValues should work on Element and Property
* TINKERPOP-2262 Improve Netty protocol handling
* TINKERPOP-2305 GraphBinary: Wrap Buffer API
* TINKERPOP-2307 Add better error message for badly configured Channelizer
* TINKERPOP-2309 Bump gremlinpython to Tornado 5.x
* TINKERPOP-2314 Employ by(String) for Map when possible and improve errors around incorrect types
* TINKERPOP-2315 Implement some form of clone() or reset() for Traversal in GLVs
* TINKERPOP-2320 [SECURITY] XMLInputFactory initialization in GraphMLReader introduces
* TINKERPOP-2322 Deprecate Jython support
* TINKERPOP-2324 Deprecate the raw NIO support in the Java driver
* TINKERPOP-2325 Generate traversals that will better yield index lookups with SPARQL
* TINKERPOP-2329 JavaScript GLV: Update websocket library dependency
* TINKERPOP-2330 JavaScript GLV should expose GraphSON2Writer and GraphSONReader

[[release-3-4-4]]
=== TinkerPop 3.4.4 (Release Date: October 14, 2019)

This release also includes changes from <<release-3-3-9, 3.3.9>>.

* Provided support for DSLs by way of remote connections through `AnonymousTraversalSource`.
* Added `elementMap()` step.
* Added GraphBinary support for Python.
* Allowed for embedded map assertions in GLV tests.
* Added `Direction` deserialization support in GLVs.

==== Bugs

* TINKERPOP-2159 EventStrategy doesn't handle multi-valued properties
* TINKERPOP-2276 No constructor for remote connection in DSL generated traversal source
* TINKERPOP-2283 GraphStep's ids null exception
* TINKERPOP-2285 Error object is unreachable
* TINKERPOP-2289 Use address instead of hostname for connection
* TINKERPOP-2290 Javascript GLV connection refused error handling
* TINKERPOP-2291 TraversalExplanation deserialization in GraphSON
* TINKERPOP-2298 Bytecode.java  flattenArguments throw exception when null
* TINKERPOP-2303 GremlinDsl generate addV instead of addE

==== Improvements

* TINKERPOP-1810 Add Lambda.binaryOperator and Lambda.unaryOperator
* TINKERPOP-1838 Python sample script
* TINKERPOP-2046 Gremlin-Python: Support custom request headers in WebSocket request
* TINKERPOP-2213 Replace scriptEvaluationTimeout in favor of something more suitable to bytecode
* TINKERPOP-2275 Update jackson databind 2.9.9.3+
* TINKERPOP-2277 Python sdk postpone the timing to create transport
* TINKERPOP-2279 GraphBinary support in Python
* TINKERPOP-2280 Prevent use of T values as property key overloads
* TINKERPOP-2284 Make it easier to return more structure of graph elements
* TINKERPOP-2302 Add isOnGraphComputer() field accessor to ElementMapStep

[[release-3-4-3]]
=== TinkerPop 3.4.3 (Release Date: August 5, 2019)

This release also includes changes from <<release-3-3-8, 3.3.8>>.

* Improved error messaging on timeouts returned to the console from `:>`.
* Added a `toString()` serializer for GraphBinary.
* Configured the Gremlin Console to use GraphBinary by default.
* Fixed transaction management for empty iterators in Gremlin Server.
* Deprecated `MessageSerializer` implementations for Gryo in Gremlin Server.
* Deprecated `Serializers` enum values of `GRYO_V1D0` and `GRYO_V3D0`.
* Deprecated `SerTokens` values of `MIME_GRYO_V1D0` and `MIME_GRYO_V3D0`.
* Added a Docker command to start Gremlin Server with the standard GLV test configurations.
* Added `aggregate(Scope,String)` and deprecated `store()` in favor of `aggregate(local)`.
* Modified `NumberHelper` to better ignore `Double.NaN` in `min()` and `max()` comparisons.
* Bumped to Netty 4.1.36.
* Bumped to Groovy 2.5.7.
* Added `userAgent` to RequestOptions. Gremlin Console sends `Gremlin Console/<version>` as the `userAgent`.
* Fixed DriverRemoteConnection ignoring `with` `Token` options when multiple were set.
* Added `:set warnings <true|false>` to Gremlin Console.

==== Bugs

* TINKERPOP-1619 TinkerGraphComputer worker count affects OptionalStep query results
* TINKERPOP-2157 SparkStarBarrierInterceptor injects (Byte) 0
* TINKERPOP-2224 Detect and fix resource leak
* TINKERPOP-2230 match() step unexpected behaviours
* TINKERPOP-2232 RemoteStrategy does not call parent class TraversalStrategy __init__
* TINKERPOP-2238 Fix remaining iterator leaks marked by @IgnoreIteratorLeak
* TINKERPOP-2241 Client exception don't match Server exception when server  throw StackOverflowError
* TINKERPOP-2248 Instability of driver for blocked requests
* TINKERPOP-2257 transaction itty  may still be visited after commit
* TINKERPOP-2264 Gremlin Python should deserialize g:Date to UTC

==== Improvements

* TINKERPOP-1084 Branch option tokens should be allowed to be traversals.
* TINKERPOP-1553 Deprecate store() in favor of aggregate(Scope)
* TINKERPOP-1921 Support hasNext terminal step in GLVs
* TINKERPOP-2020 Support withComputer() for javascript
* TINKERPOP-2223 Update jackson databind to 2.9.9
* TINKERPOP-2236 Improve error messaging for TinkerGraph IdManagers that fail on conversions
* TINKERPOP-2237 Prevent error when closing sessions that don't exist *(breaking)*
* TINKERPOP-2242 Bump to netty 4.1.36
* TINKERPOP-2243 Add user-agent to RequestOptions
* TINKERPOP-2246 Consolidate the error propagation to the client
* TINKERPOP-2250 Support toString serialization in GraphBinary
* TINKERPOP-2256 processAllStarts of AggregateStep should only be called when barrier is empty
* TINKERPOP-2260 Update jackson databind 2.9.9.1
* TINKERPOP-2265 Deprecate Traversal.getSideEffects() functionality for remoting purposes
* TINKERPOP-2270 Deprecate multi/metaproperty support in Neo4j
* TINKERPOP-2271 Add console preference to control server-originated warning display
* TINKERPOP-2272 Rename steps and tokens that conflict with standard python functions

[[release-3-4-2]]
=== TinkerPop 3.4.2 (Release Date: May 28, 2019)

This release also includes changes from <<release-3-3-7, 3.3.7>>.

* Allow a `Traversal` to know what `TraversalSource` it spawned from.
* Fixed problem with connection pool sizing and retry.
* Added status attribute for warnings to be returned to the client.
* Modified Gremlin Console to report warning status attributes.
* Changed `:>` in Gremlin Console to submit the client-side timeout on each request.
* Provided method to override the request identifier with `RequestOptions`.
* Added option to set per-request settings on a `Traversal` submitted via `Bytecode`.
* Fixed the Gryo registration for `OptionsStrategy` as it was not serializing state properly.

==== Bugs

* TINKERPOP-2090 After running backend for a day or so System.IO.IOException keep throwing
* TINKERPOP-2112 Folding in property() step is not being optimally performed
* TINKERPOP-2180 gremlin.sh doesn't work when directories contain spaces
* TINKERPOP-2183 InterpreterModeASTTransformation needs to be more specific about what it transforms
* TINKERPOP-2189 ConnectedComponent test assumes fixed order of vertices
* TINKERPOP-2194 Enforcing an order on properties in one test method of ChooseTest
* TINKERPOP-2196 PartitionStrategy with includeMetaProperties(true) can't add labeled vertex
* TINKERPOP-2198 Documentation for Store contradicts itself
* TINKERPOP-2199 within step does not work with more than two parameters with python
* TINKERPOP-2200 AddEdgeStartStep used DetachedFactory.detach instead of EventStrategy.detach
* TINKERPOP-2204 Client receives no response on failed request
* TINKERPOP-2206 Certain types in javascript don't appear to serialize with a GraphSON type
* TINKERPOP-2212 Path is not detaching properly under certain conditions
* TINKERPOP-2217 Race condition in Gremlin.net driver connection

==== Improvements

* TINKERPOP-2089 Javascript DSL support
* TINKERPOP-2179 Have o.a.t.g.driver.ser.SerializationException extend IOException
* TINKERPOP-2181 Allow ctrl+c to break out of a long running process in Gremlin Console
* TINKERPOP-2182 Remove gperfutils from Gremlin Console *(breaking)*
* TINKERPOP-2190 Document Gremlin sanitization best practices
* TINKERPOP-2191 Implement EdgeLabelVerificationStrategy
* TINKERPOP-2193 Allow a Traversal to know what TraversalSource it spawned from
* TINKERPOP-2203 Bind the console timeout to the request timeout
* TINKERPOP-2208 Include inject() in DSLs generated with Java annotation processor
* TINKERPOP-2211 Provide API to add per request option for a bytecode
* TINKERPOP-2216 Consider adding conventional status attribute key for warnings
* TINKERPOP-2219 Upgrade Netty version

[[release-3-4-1]]
=== TinkerPop 3.4.1 (Release Date: March 18, 2019)

This release also includes changes from <<release-3-3-6, 3.3.6>>.

* Gremlin.NET driver: Fixed removal of closed connections and added round-robin scheduling.
* Added GraphBinary serializer for TraversalMetrics
* Added registration for `SparqlStrategy` for GraphSON.
* Fixed up `SparqlStrategy` so that it could be used properly with `RemoteStrategy`.
* Fixed `ByteBuffer` serialization for GraphBinary.
* Fixed `Path.toString()` in `gremlin-javascript` which was referencing an invalid object.
* Fixed potential for an infinite loop in connection creation for `gremlin-dotnet`.
* Added fallback resolver to `TypeSerializerRegistry` for GraphBinary.
* Added easier to understand exceptions for connection problems in the Gremlin.Net driver.
* Support configuring the type registry builder for GraphBinary.
* Bumped to Groovy 2.5.6.
* Release working buffers in case of failure for GraphBinary.
* GraphBinary: Use the same `ByteBuf` instance to write during serialization. Changed signature of write methods in type serializers.
* Remove unused parameter in GraphBinary's `ResponseMessageSerializer`.
* Changed `SparqlTraversalSource` so as to enable Gremlin steps to be used to process results from the `sparql()` step.
* GraphBinary: Cache expression to obtain the method in `PSerializer`.

==== Bugs

* TINKERPOP-1992 count has negative time in profile
* TINKERPOP-2126 toString() methods not thread-safe
* TINKERPOP-2135 Gremlin.Net ConnectionPool doesn't handle closed idle connections properly
* TINKERPOP-2139 Errors during request serialization in WebSocketGremlinRequestEncoder/NioGremlinRequestEncoder are not reported to the client
* TINKERPOP-2141 ByteBufferSerializer modifies buffer's position
* TINKERPOP-2148 "no connection available!" is being thrown despite lots of free connections
* TINKERPOP-2152 Path toString fails in Gremlin JavaScript
* TINKERPOP-2153 Remove unused parameter from ResponseMessageSerializer *(breaking)*
* TINKERPOP-2154 GraphBinary: Serializers should release resources in case of failures
* TINKERPOP-2155 Situation can occur that causes infinite amount of connection to be opened, causing System.Net.WebSockets.WebSocketException
* TINKERPOP-2161 GraphBinary: Write serialization performance issue
* TINKERPOP-2169 Responses exceeding maxContentLength cause subsequent queries to hang
* TINKERPOP-2172 PartitionStrategy doesn't apply to AddEdgeStartStep
* TINKERPOP-2173 Incorrect reset of log level in integration test
* TINKERPOP-2177 Streaming response immediately after authentication stops after first partial response

==== Improvements

* TINKERPOP-1435 Support for extended GraphSON in gremlin-python
* TINKERPOP-1882 Apply range and limit steps as early as possible
* TINKERPOP-1998 IoGraphTest use different schemas for standard and readGraph configurations
* TINKERPOP-2088 Enable SourceLink for Gremlin.Net
* TINKERPOP-2098 Improve gremlin-server.sh help output
* TINKERPOP-2122 Expose status codes from server errors
* TINKERPOP-2124 InlineFilterStrategy produces wrong result
* TINKERPOP-2125 Extend release validation script
* TINKERPOP-2127 Add g:TraversalMetrics and g:Metrics deserializers for gremlinpython
* TINKERPOP-2129 Mask security secret or password in logs
* TINKERPOP-2130 Cannot instantiate DriverRemoteConnection without passing an options object
* TINKERPOP-2131 NoConnectionAvailableException doesn't reveal the reason
* TINKERPOP-2134 Bump to Groovy 2.5.6
* TINKERPOP-2136 Inside lower bound inclusion (documentation)
* TINKERPOP-2138 Provide a configuration to disable the global closure cache
* TINKERPOP-2140 Test build with Docker automatically
* TINKERPOP-2144 Better handle Authenticator instance failures
* TINKERPOP-2147 Add GraphBinary serializer for TraversalMetrics
* TINKERPOP-2149 GraphBinary: Make type serializer resolution pluggable
* TINKERPOP-2150 GraphBinary: Support configuring the TypeSerializerRegistry builder class in config
* TINKERPOP-2163 JavaTranslator performance enhancements
* TINKERPOP-2164 Bytecode's hashCode impl (and its inner classes) can produce hash collisions
* TINKERPOP-2165 Prefer commons-lang3 to commons-lang
* TINKERPOP-2166 GraphBinary: P deserialization should be optimized
* TINKERPOP-2167 Gremlin Javascript Traversal as async iterable
* TINKERPOP-2171 Allow SPARQL to be extended with Gremlin steps
* TINKERPOP-2174 Improve Docker Image Security

[[release-3-4-0]]
=== TinkerPop 3.4.0 (Release Date: January 2, 2019)

This release also includes changes from <<release-3-3-4, 3.3.4>> and <<release-3-3-5, 3.3.5>>.

* Changed Python "bindings" to use an actual `Bindings` object rather than a 2-tuple.
* Improved the Gremlin.NET driver: It now uses request pipelining and its `ConnectionPool` has a fixed size.
* Implemented `IndexStep` which allows to transform local collections into indexed collections or maps.
* Made `valueMap()` aware of `by` and `with` modulators and deprecated `valueMap(boolean)` overloads.
* Use `Compare.eq` in `Contains` predicates to ensure the same filter behavior for numeric values.
* Added `OptionsStrategy` to allow traversals to take arbitrary traversal-wide configurations.
* Added text predicates.
* Added `BulkSet` as a GraphSON type with support in all language variants.
* Added `ReferenceElementStrategy` to auto-detach elements to "reference" from a traversal.
* Added initial release of the GraphBinary serialization format with Java support.
* Allowed `ImportCustomizer` to accept fields.
* Removed groovy-sql dependency.
* Modified `Mutating` steps so that they are no longer marked as `final`.
* Rewrote `ConnectiveStrategy` to support an arbitrary number of infix notations in a single traversal.
* GraphSON `MessageSerializer` s will automatically register the GremlinServerModule to a provided GraphSONMapper.
* Removed support for `-i` option in Gremlin Server which was previously deprecated.
* Implemented `ShortestPathVertexProgram` and the `shortestPath()` step.
* `AbstractGraphProvider` uses `g.io()` for loading test data.
* Added the `io()` start step and `read()` and `write()` termination steps to the Gremlin language.
* Added `GraphFeatures.supportsIoRead()` and `GraphFeatures.supportsIoWrite()`.
* Deprecated `Graph.io()` and related infrastructure.
* `GraphMLReader` better handles edge and vertex properties with the same name.
* Maintained order of annotations in metrics returned from `profile()`-step.
* Refactored `TypeTranslator` to be directly extensible for `ScriptTranslator` functions.
* Bumped to Netty 4.1.25.
* Bumped to Spark 2.4.0.
* Bumped to Groovy 2.5.4.
* Modified Gremlin Server to return a "host" status attribute on responses.
* Added ability to the Java, .NET, Python and JavaScript drivers to retrieve status attributes returned from the server.
* Modified Java and Gremlin.Net `ResponseException` to include status code and status attributes.
* Modified Python `GremlinServerError` to include status attributes.
* Modified the return type for `IGremlinClient.SubmitAsync()` to be a `ResultSet` rather than an `IReadOnlyCollection`.
* Deprecated two `submit()`-related methods on the Java driver `Client` class.
* Added `Client.submit()` overloads that accept per-request `RequestOptions`.
* Added sparql-gremlin.
* Fixed a bug in dynamic Gryo registration where registrations that did not have serializers would fail.
* Moved `Parameterizing` interface to the `org.apache.tinkerpop.gremlin.process.traversal.step` package with other marker interfaces of its type.
* Replaced `Parameterizing.addPropertyMutations()` with `Configuring.configure()`.
* Changed interface hierarchy for `Parameterizing` and `Mutating` interfaces as they are tightly related.
* Introduced the `with(k,v)` and `with(k)` step modulators which can supply configuration options to `Configuring` steps.
* Added `OptionsStrategy` to allow traversals to take arbitrary traversal-wide configurations.
* Introduced the `with(k,v)` and `with(k)` traveral source configuration options which can supply configuration options to the traversal.
* Added `connectedComponent()` step and related `VertexProgram`.
* Added `supportsUpsert()` option to `VertexFeatures` and `EdgeFeatures`.
* `min()` and `max()` now support all types implementing `Comparable`.
* Change the `toString()` of `Path` to be standardized as other graph elements are.
* `hadoop-gremlin` no longer generates a test artifact.
* Allowed `GraphProvider` to expose a cached `Graph.Feature` object so that the test suite could re-use them to speed test runs.
* Fixed a bug in `ReducingBarrierStep`, that returned the provided seed value despite no elements being available.
* Changed the order of `select()` scopes. The order is now: maps, side-effects, paths.
* Moved `TraversalEngine` to `gremlin-test` as it has long been only used in testing infrastructure.
* Nested loop support added allowing `repeat()` steps to be nested.
* Events from `EventStrategy` raised from "new" mutations will now return a `KeyedVertexProperty` or `KeyedProperty` as is appropriate.
* `MutationListener#vertexPropertyChanged(Vertex, VertexProperty, Object, Object...)` no longer has a default implementation.
* Deprecated `GraphSONMessageSerializerV2d0` as it is now analogous to `GraphSONMessageSerializerGremlinV2d0`.
* Moved previously deprecated `RemoteGraph` to `gremlin-test` as it is now just a testing component.
* Removed previously deprecated `RemoteStrategy.instance()` and the strategy no longer has any connection to `RemoteGraph`.
* Removed previously deprecated methods in `SubgraphStrategy` and `PartitionStrategy` builders.
* Removed previously deprecated Credentials DSL infrastructure.
* Removed previously deprecated `RemoteConnection#submit(Traversal)` and `RemoteConnection#submit(Bytecode)` methods.
* Removed previously deprecated `MutationListener#vertexPropertyChanged(Vertex, Property, Object, Object...)`.
* Removed previously deprecated `OpSelectorHandler` constructor.
* Removed previously deprecated `close()` from `GremlinGroovyScriptEngine` which no longer implements `AutoCloseable`.
* Removed previously deprecated `getGraphInputFormat()` and `getGraphOutputFormat()` from `HadoopConfiguration`.
* Removed previously deprecated `AbstractOpProcessor#makeFrame()` method.
* Removed previously deprecated `AuthenticationSettings.className` configuration option in Gremlin Server.
* Removed previously deprecated `GraphManager` methods `getGraphs()` and `getTraversalSources()`.
* Removed previously deprecated Gremlin Server setting for `serializedResponseTimeout`.
* Removed previously deprecated Structure API exceptions related to "element not found" situations.
* Removed previously deprecated `rebindings` options from the Java driver API.
* Removed previously deprecated `LambdaCollectingBarrierStep.Consumers` enum.
* Removed previously deprecated `HasContainer#makeHasContainers(String, P)`
* Removed support for Giraph.
* Removed previously deprecated JavaScript Driver property `traversers` of the `ResultSet`.
* gremlin-python: use explicit Bindings object for python instead of a 2-tuple

==== Bugs

* TINKERPOP-1777 Gremlin .max step returns -2147483648 for empty result sets *(breaking)*
* TINKERPOP-1869 Profile step and iterate do not play nicely with each other
* TINKERPOP-1898 Issue with bindings in strategies and lambdas
* TINKERPOP-1927 Gherkin scenario expects list with duplicates, but receives g:Set
* TINKERPOP-1933 gremlin-python maximum recursion depth exceeded on large responses
* TINKERPOP-1947 Path history isn't preserved for keys in mutations
* TINKERPOP-1949 Formatting error on website
* TINKERPOP-1958 TinkerGraphCountStrategy can return wrong counts
* TINKERPOP-1961 Duplicate copies of images directory in docs
* TINKERPOP-1962 GroovyTranslator doesn't handle empty maps
* TINKERPOP-1963 Use of reducing step in choose()
* TINKERPOP-1972 inject() tests are throwing exceptions in .NET GLV tests
* TINKERPOP-1978 Check for Websocket connection state when retrieved from Connection Pool missing
* TINKERPOP-1979 Several OLAP issues in MathStep
* TINKERPOP-1988 minor error in documentation
* TINKERPOP-1999 [Java][gremlin-driver] Query to a remote server via the websocket client hangs indefinitely if the server becomes unavailable
* TINKERPOP-2005 Intermittent NullPointerException in response handling
* TINKERPOP-2006 GraphML serialization invalid if a vertex and edge have similar named property
* TINKERPOP-2009 Pick.any and Pick.none should be exposed in Gremlin-JavaScript
* TINKERPOP-2021 Prevent maximum recursion depth failure
* TINKERPOP-2028 AbstractGraphSONMessageSerializerV2d0 should register GremlinServerModule when mapper is provided
* TINKERPOP-2029 ConcurrentModificationException for InlineFilterStrategy
* TINKERPOP-2030 KeepAlive task executed for every Connection.write call
* TINKERPOP-2032 Update jython-standalone
* TINKERPOP-2044 Cannot reconnect to Azure cosmos host that becomes available again
* TINKERPOP-2058 Contains predicates should rely on Compare predicates *(breaking)*
* TINKERPOP-2081 PersistedOutputRDD materialises rdd lazily with Spark 2.x
* TINKERPOP-2091 Wrong/Missing feature requirements in StructureStandardTestSuite
* TINKERPOP-2094 Gremlin Driver Cluster Builder serializer method does not use mimeType as suggested
* TINKERPOP-2095 GroupStep looks for irrelevant barrier steps
* TINKERPOP-2096 gremlinpython: AttributeError when connection is closed before result is received
* TINKERPOP-2100 coalesce() creating unexpected results when used with order()
* TINKERPOP-2113 P.Within() doesn't work when given a List argument

==== Improvements

* TINKERPOP-550 Gremlin IO needs to support both OLTP and OLAP naturally.
* TINKERPOP-967 Support nested-repeat() structures
* TINKERPOP-1113 GraphComputer subclasses should support native methods
* TINKERPOP-1143 Remove deprecated TraversalSource.Builder and TraversalEngine. *(breaking)*
* TINKERPOP-1296 Remove deprecated serializedResponseTimeout from Gremlin Server *(breaking)*
* TINKERPOP-1342 Allow setting scriptEvaluationTimeout in driver
* TINKERPOP-1365 Log the seed used to initialize Random in tests
* TINKERPOP-1410 mvn install -Dmaven.test.skip=true doesn't work on a clean machine *(breaking)*
* TINKERPOP-1446 Add a StringFactory for Path which prefixes with type.
* TINKERPOP-1447 Add some JavaScript intelligence to the documentation so that comments and output are not copied in a copy paste
* TINKERPOP-1494 Means of exposing execution information from a result produced by RemoteConnection
* TINKERPOP-1518 Provide a way for providers to expose static Graph.Features to tests
* TINKERPOP-1522 Order of select() scopes *(breaking)*
* TINKERPOP-1595 Go through TraversalVertexProgram with a profile and optimize.
* TINKERPOP-1628 Implement TraversalSelectStep
* TINKERPOP-1685 Introduce optional feature to allow for upserts without read-before-write
* TINKERPOP-1705 Remove deprecated rebindings option *(breaking)*
* TINKERPOP-1707 Remove deprecated AuthenticationSettings.className option *(breaking)*
* TINKERPOP-1755 No docs for ReferenceElements
* TINKERPOP-1769 Python graph[empty] string representation is confusing
* TINKERPOP-1774 Gremlin .NET: Support min and max sizes in Connection pool
* TINKERPOP-1775 Gremlin .NET: Implement a Connection write queue to support request pipelining
* TINKERPOP-1778 Do not promote timedInterrupt option for Gremlin Server script processing
* TINKERPOP-1780 Add authentication tests for gremlin-python
* TINKERPOP-1831 Refactor EventStrategy  *(breaking)*
* TINKERPOP-1836 .NET sample project
* TINKERPOP-1841 Include Python GLV tests on TravisCI
* TINKERPOP-1849 Provide a way to fold() with an index
* TINKERPOP-1864 Gremlin Python tests for GraphSON 2.0 and 3.0
* TINKERPOP-1878 Sparql to Gremlin Compiler
* TINKERPOP-1888 Extend max and min to all Comparable properties, not just Numbers *(breaking)*
* TINKERPOP-1889 JavaScript GLV: Use heartbeat to prevent connection timeout
* TINKERPOP-1897 Provide Docker images of Gremlin Server and Console
* TINKERPOP-1906 Make ResponseException explorable
* TINKERPOP-1912 Remove MD5 checksums
* TINKERPOP-1913 Expose metadata from Gremlin Server to Clients
* TINKERPOP-1930 Drop support for Giraph *(breaking)*
* TINKERPOP-1934 Bump to latest version of httpclient
* TINKERPOP-1936 Performance enhancement to Bytecode deserialization
* TINKERPOP-1941 Remove deprecated Structure API exception methods *(breaking)*
* TINKERPOP-1942 Binary serialization format
* TINKERPOP-1945 Add support for extended GraphSon types to Gremlin.net
* TINKERPOP-1946 Remove the deprecated Credentials DSL infrastructure *(breaking)*
* TINKERPOP-1950 Traversal construction performance enhancements
* TINKERPOP-1951 gremlin-server.bat doesn't support paths containing spaces
* TINKERPOP-1953 Bump to Groovy 2.4.15
* TINKERPOP-1954 Remove deprecated GraphManager methods *(breaking)*
* TINKERPOP-1959 Provide a way to submit scripts to the server in gremlin-javascript
* TINKERPOP-1967 Add a connectedComponent() step
* TINKERPOP-1968 Refactor elements of Gremlin Server testing
* TINKERPOP-1975 Introduce with() step modulator *(breaking)*
* TINKERPOP-1976 Include Computer tests for GLVs
* TINKERPOP-1977 Gremlin-JavaScript: Support SASL authentication
* TINKERPOP-1984 Allow support for multiple serializer versions in Gremlin Server HTTP *(breaking)*
* TINKERPOP-1985 Update position on bulk loading
* TINKERPOP-1986 Remove deprecation from PartitionStrategy, SubgraphStrategy and GremlinScriptEngine *(breaking)*
* TINKERPOP-1987 Bump to Netty 4.1.x
* TINKERPOP-1989 Preserve order that plugins are applied in Gremlin Console
* TINKERPOP-1990 Add a shortestPath() step
* TINKERPOP-1993 Bump to Spark 2.3.1
* TINKERPOP-1995 DriverRemoteConnection close() method returns undefined
* TINKERPOP-1996 Introduce read() and write() steps
* TINKERPOP-2002 Create a blog post explaining the value of using TinkerPop
* TINKERPOP-2010 Generate jsdoc for gremlin-javascript
* TINKERPOP-2011 Use NumberHelper on choose()
* TINKERPOP-2012 Target .NET Standard 2.0 for Gremlin.Net
* TINKERPOP-2013 Process tests that are auto-ignored stink
* TINKERPOP-2015 Allow users to configure the WebSocket connections
* TINKERPOP-2016 Upgrade Jackson FasterXML to 2.9.5 or later to fix security vulnerability
* TINKERPOP-2017 Check for Column in by()
* TINKERPOP-2018 Generate API docs for Gremlin.Net
* TINKERPOP-2022 Cluster SSL should trust default ca certs by default
* TINKERPOP-2023 Gremlin Server should not create self-signed certs *(breaking)*
* TINKERPOP-2024 Gremlin Server Application archetype should connect via withRemote
* TINKERPOP-2025 Change to SHA-256/512 and drop SHA-1 for releases
* TINKERPOP-2026 Gremlin.Net.Driver should check ClientWebSocket.State before closing
* TINKERPOP-2031 Remove support for -i in gremlin-server.sh *(breaking)*
* TINKERPOP-2033 Maintain order of profile() annotations
* TINKERPOP-2034 Register synchronizedMap() with Gryo
* TINKERPOP-2037 Remove unused groovy-sql dependency
* TINKERPOP-2038 Make groovy script cache size configurable
* TINKERPOP-2039 Bump to Groovy 2.5.2 *(breaking)*
* TINKERPOP-2040 Improve flexibility of GroovyTranslator to handle custom types
* TINKERPOP-2041 Text Predicates
* TINKERPOP-2045 Remove non-indy groovy dependencies
* TINKERPOP-2049 Single argument with() overload
* TINKERPOP-2050 Add a :bytecode command to Gremlin Console
* TINKERPOP-2053 Provider OptionsStrategy for traversal configurations
* TINKERPOP-2055 Provide support for special number cases like Infinity in GraphSON
* TINKERPOP-2056 Use NumberHelper in Compare
* TINKERPOP-2059 Modulation of valueMap() *(breaking)*
* TINKERPOP-2060 Make Mutating steps non-final
* TINKERPOP-2061 Add with() configuration as global to a traversal
* TINKERPOP-2062 Add Traversal class to CoreImports
* TINKERPOP-2064 Add status attributes to results for gremlin-javascript
* TINKERPOP-2065 Optimize iterate() for remote traversals
* TINKERPOP-2066 Bump to Groovy 2.5.3
* TINKERPOP-2067 Allow getting raw data from Gremlin.Net.Driver.IGremlinClient
* TINKERPOP-2068 Bump Jackson Databind 2.9.7
* TINKERPOP-2069 Document configuration of Gremlin.Net
* TINKERPOP-2070 gremlin-javascript: Introduce Connection representation
* TINKERPOP-2071 gremlin-python: the graphson deserializer for g:Set should return a python set
* TINKERPOP-2072 Refactor custom type translation for ScriptTranslators *(breaking)*
* TINKERPOP-2073 Generate tabs for static code blocks
* TINKERPOP-2074 Ensure that only NuGet packages for the current version are pushed
* TINKERPOP-2075 Introduce ReferenceElementStrategy
* TINKERPOP-2077 VertexProgram.Builder should have a default create() method with no Graph
* TINKERPOP-2078 Hide use of EmptyGraph or RemoteGraph behind a more unified method for TraversalSource construction
* TINKERPOP-2079 Move RemoteGraph to test package *(breaking)*
* TINKERPOP-2084 For remote requests in console display the remote stack trace
* TINKERPOP-2092 Deprecate default GraphSON serializer fields
* TINKERPOP-2093 Bump to Groovy 2.5.4
* TINKERPOP-2097 Create a DriverRemoteConnection with an initialized Client
* TINKERPOP-2101 Support Spark 2.4
* TINKERPOP-2103 Remove deprecated submit() options on RemoteConnection *(breaking)*
* TINKERPOP-2104 Allow ImportCustomizer to handle fields
* TINKERPOP-2106 When gremlin executes timeout, throw TimeoutException instead of TraversalInterruptedException/InterruptedIOException
* TINKERPOP-2110 Allow Connection on Different Path (from /gremlin)
* TINKERPOP-2111 Add BulkSet as a GraphSON type *(breaking)*
* TINKERPOP-2114 Document common Gremlin anti-patterns
* TINKERPOP-2116 Explicit Bindings object for Python *(breaking)*
* TINKERPOP-2117 gremlin-python: Provide a better data structure for a Binding
* TINKERPOP-2119 Validate C# code samples in docs
* TINKERPOP-2121 Bump Jackson Databind 2.9.8

== TinkerPop 3.3.0 (Gremlin Symphony #40 in G Minor)

image::https://raw.githubusercontent.com/apache/tinkerpop/master/docs/static/images/gremlin-mozart.png[width=185]

[[release-3-3-11]]
=== TinkerPop 3.3.11 (Release Date: June 1, 2020)

* Added `trustStoreType` such that keystore and truststore can be of different types in the Java driver.
* Added session support to all GLVs: Javascript, .NET and Python.
* Fixed bug in Gremlin Server shutdown if failures occurred during `GraphManager` initialization.
* Modified Gremlin Server to close the session when the channel itself is closed.
* Fixed bug in `Order` where comparisons of `enum` types wouldn't compare with `String` values.
* Added `maxWaitForClose` configuration option to the Java driver.
* Deprecated `maxWaitForSessionClose` in the Java driver.
* Bumped to Jackson 2.9.10.4.
* Remove invalid service descriptors from gremlin-shaded.
* Fixed bug in Python and .NET traversal `clone()` where deep copies of bytecode were not occurring.
* Fixed bug where `profile()` was forcing `LazyBarrierStrategy` to add an extra `barrier()` to the end of traversals.
* Fixed bug in Python about integer serializer which was out of range of `g:Int32`
* Bumped commons-codec 1.14

==== Bugs

* TINKERPOP-2347 Remove invalid service descriptors from gremlin-shaded
* TINKERPOP-2350 clone() is not deep copying Traversal internals
* TINKERPOP-2351 Local Map ordering of keys can generate cast errors
* TINKERPOP-2353 Error while Shutting Down Gremlin Server
* TINKERPOP-2355 Jackson-databind version in Gremlin shaded dependency needs to be increased  - introduces vulnerability issues
* TINKERPOP-2360 failed to deserializer int32 when gremlin-python submit bytecode with a big int value
* TINKERPOP-2365 LazyBarrierStrategy adds a NoOpBarrierStep when profile() is present

==== Improvements

* TINKERPOP-2336 Allow close of channel without having to wait for server
* TINKERPOP-2339 Gremlin.Net: Update System.Net.WebSockets.Client dependency
* TINKERPOP-2354 Document recommendation to reuse graph traversal source

[[release-3-3-10]]
=== TinkerPop 3.3.10 (Release Date: February 3, 2020)

* Improved error messaging for a `Cluster` with a bad `Channelizer` configuration in the Java driver.
* Made `Cluster` be able to open configuration file on resources directory.
* Implemented `Traversal.clone()` operations for all language variants.
* Refactored `PathProcessorStrategy` to use the marker model.
* Bumped to Tornado 5.x for gremlin-python.
* Started keep-alive polling on `Connection` construction to ensure that a `Connection` doesn't die in the pool.
* Deprecated `TraversalStrategies.applyStrategies()`.
* Deprecated Jython support in `gremlin-python`.
* Deprecated `NioChannelizer` and related classes in `gremlin-driver` and `gremlin-server`.
* Fixed a bug in the `ClassCacheRequestCount` metric for `GremlinGroovyScriptEngine` which wasn't including the cache hit count, only the misses.
* Improved Gremlin Server executor thread handling on client close requests.
* Reverted: Modified Java driver to use IP address rather than hostname to create connections.
* Allow custom XMLInputFactory to be used with GraphMLReader.

==== Bugs

* TINKERPOP-2175 Executor thread is not returned on channel close
* TINKERPOP-2266 Keep alive not started at connection creation
* TINKERPOP-2274 Test of TinkerGraph Gremlin fail on Windows and non EN locale
* TINKERPOP-2332 JavaScript GLV: structure element toString() should internally call toString()
* TINKERPOP-2333 JavaScript GLV: GraphSON2/3 Edge deserialization is invalid

==== Improvements

* TINKERPOP-2307 Add better error message for badly configured Channelizer
* TINKERPOP-2309 Bump gremlinpython to Tornado 5.x
* TINKERPOP-2315 Implement some form of clone() or reset() for Traversal in GLVs
* TINKERPOP-2320 [SECURITY] XMLInputFactory initialization in GraphMLReader introduces
* TINKERPOP-2322 Deprecate Jython support
* TINKERPOP-2324 Deprecate the raw NIO support in the Java driver
* TINKERPOP-2329 JavaScript GLV: Update websocket library dependency
* TINKERPOP-2330 JavaScript GLV should expose GraphSON2Writer and GraphSONReader

[[release-3-3-9]]
=== TinkerPop 3.3.9 (Release Date: October 14, 2019)

* Exposed response status attributes in a `ResponseError` in gremlin-javascript.
* Added `ImmutableExplanation` for a `TraversalExplanation` that just contains data.
* Added support for `UnaryOperator` and `BinaryOperator` for `Lambda` instances.
* Fixed `TraversalExplanation` deserialization in GraphSON 2 and 3 which was not supported before in Java.
* Added support for custom request headers in Python.
* Fixed Java DSL annotation for generation of `addE()` which was formerly calling the wrong step.
* Deprecated `scriptEvaluationTimeout` in favor of the more generic `evaluationTimeout`.
* Bumped jackson-databind to 2.9.10 due to CVE-2019-14379, CVE-2019-14540, CVE-2019-16335.
* Added `ReservedKeysVerificationStrategy` to allow warnings or exceptions when certain keys are used for properties.
* Added the `AbstractWarningVerificationStrategy` base class for "warning" style `VerificationStrategy` implementations.
* Refactored `EdgeLabelVerificationStrategy` to use `AbstractWarningVerificationStrategy`.
* Added `EdgeLabelVerificationStrategy` to Python.
* Improved handling of `null` values in bytecode construction.
* Fixed Java driver authentication problems when calling the driver from multiple threads.
* Modified Java driver to use IP address rather than hostname to create connections.
* Fixed potential for `NullPointerException` with empty identifiers in `GraphStep`.
* Postponed the timing of transport creation to `connection.write` in Gremlin Python.
* Made `EventStrategy` compatible with multi-valued properties.
* Changed `TraversalOpProcessor` to throw a `SERVER_ERROR_SCRIPT_EVALUATION` (597) if lambdas don't compile.
* Bumped `commons-compress` to 1.19 due to CVE-2018-11771.
* gremlin-javascript: Use `socketError` Connection event to prevent exit on error and expose Connection events.

==== Bugs

* TINKERPOP-2159 EventStrategy doesn't handle multi-valued properties
* TINKERPOP-2283 GraphStep's ids null exception
* TINKERPOP-2285 Error object is unreachable
* TINKERPOP-2289 Use address instead of hostname for connection
* TINKERPOP-2290 Javascript GLV connection refused error handling
* TINKERPOP-2291 TraversalExplanation deserialization in GraphSON
* TINKERPOP-2298 Bytecode.java  flattenArguments throw exception when null
* TINKERPOP-2303 GremlinDsl generate addV instead of addE

==== Improvements

* TINKERPOP-1810 Add Lambda.binaryOperator and Lambda.unaryOperator
* TINKERPOP-1838 Python sample script
* TINKERPOP-2046 Gremlin-Python: Support custom request headers in WebSocket request
* TINKERPOP-2213 Replace scriptEvaluationTimeout in favor of something more suitable to bytecode
* TINKERPOP-2275 Update jackson databind 2.9.9.3+
* TINKERPOP-2277 Python sdk postpone the timing to create transport
* TINKERPOP-2280 Prevent use of T values as property key overloads

[[release-3-3-8]]
=== TinkerPop 3.3.8 (Release Date: August 5, 2019)

* Provided support for `withComputer()` in gremlin-javascript.
* Deprecated remote traversal side-effect retrieval and related infrastructure.
* Bumped to Groovy 2.4.17.
* Bumped to Jackson Databind 2.9.9.1.
* Fixed bug with Python in `g:Date` of GraphSON where local time zone was being used during serialization/deserialization.
* Improved error messaging when an attempt is made to serialize multi-properties to GraphML.
* Deprecated multi/meta-property support in `Neo4jGraph`.
* Improved exception and messaging for gt/gte/lt/lte when one of the object isn't a `Comparable`.
* Added test infrastructure to check for storage iterator leak.
* Fixed multiple iterator leaks in query processor.
* Fixed `optional()` so that the child traversal is treated as local.
* Changed default keep-alive time for driver to 3 minutes.
* Fixed bug where server-side keep-alive was not always disabled when its setting was zero.
* Added support for `hasNext()` in Javascript and .NET.
* Improved error messaging for invalid inputs to the TinkerGraph `IdManager` instances.
* Forced replacement of connections in Java driver for certain exception types that seem to ultimately kill the connection.
* Changed the `reverse()` of `desc` and `asc` on `Order` to not use the deprecated `decr` and `incr`.
* Fixed bug in `MatchStep` where the correct was not properly determined.
* Fixed bug where client/server exception mismatch when server throw StackOverflowError
* Added underscore suffixed steps and tokens in Gremlin-Python that conflict with global function names.
* Prevent exception when closing a session that doesn't exist.
* Allow predicates and traversals to be used as options in `BranchStep`.
* Ensure only a single final response is sent to the client with Gremlin Server.
* Deprecated `ResponseHandlerContext` with related infrastructure and folded its functionality into `Context` in Gremlin Server.
* Improved performance of `aggregate()` by avoiding excessive calls to `hasNext()` when the barrier is empty.

==== Bugs

* TINKERPOP-1619 TinkerGraphComputer worker count affects OptionalStep query results
* TINKERPOP-2224 Detect and fix resource leak
* TINKERPOP-2230 match() step unexpected behaviours
* TINKERPOP-2232 RemoteStrategy does not call parent class TraversalStrategy __init__
* TINKERPOP-2238 Fix remaining iterator leaks marked by @IgnoreIteratorLeak
* TINKERPOP-2241 Client exception don't match Server exception when server  throw StackOverflowError
* TINKERPOP-2248 Instability of driver for blocked requests
* TINKERPOP-2264 Gremlin Python should deserialize g:Date to UTC

==== Improvements

* TINKERPOP-1084 Branch option tokens should be allowed to be traversals.
* TINKERPOP-1921 Support hasNext terminal step in GLVs
* TINKERPOP-2020 Support withComputer() for javascript
* TINKERPOP-2223 Update jackson databind to 2.9.9
* TINKERPOP-2236 Improve error messaging for TinkerGraph IdManagers that fail on conversions
* TINKERPOP-2237 Prevent error when closing sessions that don't exist *(breaking)*
* TINKERPOP-2246 Consolidate the error propagation to the client
* TINKERPOP-2256 processAllStarts of AggregateStep should only be called when barrier is empty
* TINKERPOP-2260 Update jackson databind 2.9.9.1
* TINKERPOP-2265 Deprecate Traversal.getSideEffects() functionality for remoting purposes
* TINKERPOP-2270 Deprecate multi/metaproperty support in Neo4j
* TINKERPOP-2272 Rename steps and tokens that conflict with standard python functions

[[release-3-3-7]]
=== TinkerPop 3.3.7 (Release Date: May 28, 2019)

* Developed DSL pattern for gremlin-javascript.
* Generated uberjar artifact for Gremlin Console.
* Improved folding of `property()` step into related mutating steps.
* Added `inject()` to steps generated on the DSL `TraversalSource`.
* Removed `gperfutils` dependencies from Gremlin Console.
* Fixed `PartitionStrategy` when setting vertex label and having `includeMetaProperties` configured to `true`.
* Ensure `gremlin.sh` works when directories contain spaces.
* Prevented client-side hangs if metadata generation fails on the server.
* Fixed bug with `EventStrategy` in relation to `addE()` where detachment was not happening properly.
* Ensured that `gremlin.sh` works when directories contain spaces.
* Fixed bug in detachment of `Path` where embedded collection objects would prevent that process.
* Enabled `ctrl+c` to interrupt long running processes in Gremlin Console.
* Quieted "host unavailable" warnings for both the driver and Gremlin Console.
* Fixed construction of `g:List` from arrays in gremlin-javascript.
* Fixed bug in `GremlinGroovyScriptEngine` interpreter mode around class definitions.
* Implemented `EdgeLabelVerificationStrategy`.
* Fixed behavior of `P` for `within()` and `without()` in GLVs to be consistent with Java when using varargs.
* Cleared the input buffer after exceptions in Gremlin Console.
* Added parameter to configure the `processor` in the gremlin-javascript `client` constructor.
* Bumped `Netty` to 4.1.32.

==== Bugs

* TINKERPOP-2112 Folding in property() step is not being optimally performed
* TINKERPOP-2180 gremlin.sh doesn't work when directories contain spaces
* TINKERPOP-2183 InterpreterModeASTTransformation needs to be more specific about what it transforms
* TINKERPOP-2194 Enforcing an order on properties in one test method of ChooseTest
* TINKERPOP-2196 PartitionStrategy with includeMetaProperties(true) can't add labeled vertex
* TINKERPOP-2198 Documentation for Store contradicts itself
* TINKERPOP-2199 within step does not work with more than two parameters with python
* TINKERPOP-2200 AddEdgeStartStep used DetachedFactory.detach instead of EventStrategy.detach
* TINKERPOP-2204 Client receives no response on failed request
* TINKERPOP-2206 Certain types in javascript don't appear to serialize with a GraphSON type
* TINKERPOP-2212 Path is not detaching properly under certain conditions

==== Improvements

* TINKERPOP-2089 Javascript DSL support
* TINKERPOP-2179 Have o.a.t.g.driver.ser.SerializationException extend IOException
* TINKERPOP-2181 Allow ctrl+c to break out of a long running process in Gremlin Console
* TINKERPOP-2182 Remove gperfutils from Gremlin Console *(breaking)*
* TINKERPOP-2191 Implement EdgeLabelVerificationStrategy
* TINKERPOP-2211 Provide API to add per request option for a bytecode

[[release-3-3-6]]
=== TinkerPop 3.3.6 (Release Date: March 18, 2019)

* Docker images use user `gremlin` instead of `root`
* Added a new `ResponseStatusCode` for client-side serialization errors.
* Refactored use of `commons-lang` to use `common-lang3` only, though dependencies may still use `commons-lang`.
* Bumped `commons-lang3` to 3.8.1.
* Improved handling of client-side serialization errors that were formerly just being logged rather than being raised.
* Add Python `TraversalMetrics` and `Metrics` deserializers.
* Masked sensitive configuration options in the logs of `KryoShimServiceLoader`.
* Added `globalFunctionCacheEnabled` to the `GroovyCompilerGremlinPlugin` to allow that cache to be disabled.
* Added `globalFunctionCacheEnabled` override to `SessionOpProcessor` configuration.
* Added status code to `GremlinServerError` so that it would be more directly accessible during failures.
* Added GraphSON serialization support for `Duration`, `Char`, `ByteBuffer`, `Byte`, `BigInteger` and `BigDecimal` in `gremlin-python`.
* Added `ProfilingAware` interface to allow steps to be notified that `profile()` was being called.
* Fixed bug where `profile()` could produce negative timings when `group()` contained a reducing barrier.
* Improved logic determining the dead or alive state of a Java driver `Connection`.
* Improved handling of dead connections and the availability of hosts.
* Bumped `httpclient` to 4.5.7.
* Bumped `slf4j` to 1.7.25.
* Bumped `commons-codec` to 1.12.
* Bumped to Groovy 2.5.6.
* Bumped to Hadoop 2.7.7.
* Fixed partial response failures when using authentication in `gremlin-python`.
* Fixed concurrency issues in `TraverserSet.toString()` and `ObjectWritable.toString()`.
* Fixed a bug in `InlineFilterStrategy` that mixed up and's and or's when folding merging conditions together.
* Fixed a bug in `PartitionStrategy` where `addE()` as a start step was not applying the partition.
* Improved handling of failing `Authenticator` instances thus improving server responses to drivers.
* Improved performance of `JavaTranslator` by reducing calls to `Method.getParameters()`.
* Implemented `EarlyLimitStrategy` which is supposed to significantly reduce backend operations for queries that use `range()`.
* Reduced chance of hash collisions in `Bytecode` and its inner classes.
* Added `Symbol.asyncIterator` member to the `Traversal` class to provide support for `await ... of` loops (async iterables).

==== Bugs

* TINKERPOP-2081 PersistedOutputRDD materialises rdd lazily with Spark 2.x
* TINKERPOP-2091 Wrong/Missing feature requirements in StructureStandardTestSuite
* TINKERPOP-2094 Gremlin Driver Cluster Builder serializer method does not use mimeType as suggested
* TINKERPOP-2095 GroupStep looks for irrelevant barrier steps
* TINKERPOP-2096 gremlinpython: AttributeError when connection is closed before result is received
* TINKERPOP-2100 coalesce() creating unexpected results when used with order()
* TINKERPOP-2105 Gremlin-Python connection not returned back to the pool on exception from gremlin server
* TINKERPOP-2113 P.Within() doesn't work when given a List argument

==== Improvements

* TINKERPOP-1889 JavaScript GLV: Use heartbeat to prevent connection timeout
* TINKERPOP-2010 Generate jsdoc for gremlin-javascript
* TINKERPOP-2013 Process tests that are auto-ignored stink
* TINKERPOP-2018 Generate API docs for Gremlin.Net
* TINKERPOP-2038 Make groovy script cache size configurable
* TINKERPOP-2050 Add a :bytecode command to Gremlin Console
* TINKERPOP-2062 Add Traversal class to CoreImports
* TINKERPOP-2065 Optimize iterate() for remote traversals
* TINKERPOP-2067 Allow getting raw data from Gremlin.Net.Driver.IGremlinClient
* TINKERPOP-2068 Bump Jackson Databind 2.9.7
* TINKERPOP-2069 Document configuration of Gremlin.Net
* TINKERPOP-2070 gremlin-javascript: Introduce Connection representation
* TINKERPOP-2071 gremlin-python: the graphson deserializer for g:Set should return a python set
* TINKERPOP-2073 Generate tabs for static code blocks
* TINKERPOP-2074 Ensure that only NuGet packages for the current version are pushed
* TINKERPOP-2077 VertexProgram.Builder should have a default create() method with no Graph
* TINKERPOP-2078 Hide use of EmptyGraph or RemoteGraph behind a more unified method for TraversalSource construction
* TINKERPOP-2084 For remote requests in console display the remote stack trace
* TINKERPOP-2092 Deprecate default GraphSON serializer fields
* TINKERPOP-2097 Create a DriverRemoteConnection with an initialized Client
* TINKERPOP-2102 Deprecate static fields on TraversalSource related to remoting
* TINKERPOP-2106 When gremlin executes timeout, throw TimeoutException instead of TraversalInterruptedException/InterruptedIOException
* TINKERPOP-2110 Allow Connection on Different Path (from /gremlin)
* TINKERPOP-2114 Document common Gremlin anti-patterns
* TINKERPOP-2118 Bump to Groovy 2.4.16
* TINKERPOP-2121 Bump Jackson Databind 2.9.8

[[release-3-3-5]]
=== TinkerPop 3.3.5 (Release Date: January 2, 2019)

This release also includes changes from <<release-3-2-11, 3.2.11>>.

* Fixed and/or folding in `InlineFilterStrategy`.
* Fixed configuration and serialization of `SubgraphStrategy` which was missing the `checkAdjacentVertices` flag.
* Captured `TraversalInterruptionException` and converted to `TimeoutException` for `GremlinExecutor`.
* Fixed a bug in `CoalesceStep` which squared the bulk if the step followed a `Barrier` step.
* Fixed a bug in `GroupStep` that assigned wrong reducing bi-operators
* Added `:bytecode` command to help developers debugging `Bytecode`-based traversals.
* Added option to set the path for the URI on the Java driver.
* Fixed `PersistedOutputRDD` to eager persist RDD by adding `count()` action calls.
* Deserialized `g:Set` to a Python `Set` in GraphSON in `gremlin-python`.
* Deprecated `StarGraph.builder()` and `StarGraph.Builder.build()` in favor of the more common "builder" patterns of `build()` and `create()` respectively.
* Deprecated `Serializers.DEFAULT_RESULT_SERIALIZER` and `DEFAULT_REQUEST_SERIALIZER`.
* Deprecated `TraversalSource#GREMLIN_REMOTE` and `TraversalSource#GREMLIN_REMOTE_CONNECTION_CLASS` moving them to `RemoteConnection`.
* Fixed the setting of the default label for a `ReferenceVertex` when the original vertex was of type `ComputerAdjacentVertex`.
* Changed Java driver to expect a generic `RemoteTraverser` object rather than the specific `DefaultRemoteTraverser`.
* Better handled server disconnect condition for the `gremlin-python` driver by throwing a clear exception.
* Display the remote stack trace in the Gremlin Console when scripts sent to the server fail.
* Added `AnonymousTraversalSource` which provides a more unified means of constructing a `TraversalSource`.
* Added `DriverRemoteConnection.using(Client)` to provide users better control over the number of connections being created.
* Changed behavior of GraphSON deserializer in gremlin-python such that `g:Set` returns a Python `Set`.
* Bumped to Groovy 2.4.16.
* Fixed bug that prevented `TraversalExplanation` from serializing properly with GraphSON.
* Changed behavior of `iterate()` in Python, Javascript and .NET to send `none()` thus avoiding unnecessary results being returned.
* Provided for a configurable class map cache in the `GremlinGroovyScriptEngine` and exposed that in Gremlin Server.
* `GraphProvider` instances can be annotated with `OptOut` configurations that will be applied in addition to the `OptOut` instances on a `Graph`.

==== Bugs

* TINKERPOP-2081 PersistedOutputRDD materialises rdd lazily with Spark 2.x
* TINKERPOP-2091 Wrong/Missing feature requirements in StructureStandardTestSuite
* TINKERPOP-2094 Gremlin Driver Cluster Builder serializer method does not use mimeType as suggested
* TINKERPOP-2095 GroupStep looks for irrelevant barrier steps
* TINKERPOP-2096 gremlinpython: AttributeError when connection is closed before result is received
* TINKERPOP-2100 coalesce() creating unexpected results when used with order()
* TINKERPOP-2113 P.Within() doesn't work when given a List argument

==== Improvements

* TINKERPOP-1889 JavaScript GLV: Use heartbeat to prevent connection timeout
* TINKERPOP-2010 Generate jsdoc for gremlin-javascript
* TINKERPOP-2013 Process tests that are auto-ignored stink
* TINKERPOP-2018 Generate API docs for Gremlin.Net
* TINKERPOP-2038 Make groovy script cache size configurable
* TINKERPOP-2050 Add a :bytecode command to Gremlin Console
* TINKERPOP-2062 Add Traversal class to CoreImports
* TINKERPOP-2065 Optimize iterate() for remote traversals
* TINKERPOP-2067 Allow getting raw data from Gremlin.Net.Driver.IGremlinClient
* TINKERPOP-2069 Document configuration of Gremlin.Net
* TINKERPOP-2070 gremlin-javascript: Introduce Connection representation
* TINKERPOP-2071 gremlin-python: the graphson deserializer for g:Set should return a python set
* TINKERPOP-2073 Generate tabs for static code blocks
* TINKERPOP-2074 Ensure that only NuGet packages for the current version are pushed
* TINKERPOP-2077 VertexProgram.Builder should have a default create() method with no Graph
* TINKERPOP-2078 Hide use of EmptyGraph or RemoteGraph behind a more unified method for TraversalSource construction
* TINKERPOP-2084 For remote requests in console display the remote stack trace
* TINKERPOP-2092 Deprecate default GraphSON serializer fields
* TINKERPOP-2097 Create a DriverRemoteConnection with an initialized Client
* TINKERPOP-2102 Deprecate static fields on TraversalSource related to remoting
* TINKERPOP-2106 When gremlin executes timeout, throw TimeoutException instead of TraversalInterruptedException/InterruptedIOException
* TINKERPOP-2110 Allow Connection on Different Path (from /gremlin)
* TINKERPOP-2114 Document common Gremlin anti-patterns
* TINKERPOP-2118 Bump to Groovy 2.4.16
* TINKERPOP-2121 Bump Jackson Databind 2.9.8

[[release-3-3-4]]
=== TinkerPop 3.3.4 (Release Date: October 15, 2018)

This release also includes changes from <<release-3-2-10, 3.2.10>>.

* Added synchronized `Map` to Gryo 3.0 registrations.
* Removed `timedInterrupt` from documentation as a way to timeout.
* Deprecated `Order` for `incr` and `decr` in favor of `asc` and `desc`.
* Fixed bug in `math()` for OLAP where `ComputerVerificationStrategy` was incorrectly detecting path label access and preventing execution.

==== Bugs

* TINKERPOP-1898 Issue with bindings in strategies and lambdas
* TINKERPOP-1933 gremlin-python maximum recursion depth exceeded on large responses
* TINKERPOP-1958 TinkerGraphCountStrategy can return wrong counts
* TINKERPOP-1961 Duplicate copies of images directory in docs
* TINKERPOP-1962 GroovyTranslator doesn't handle empty maps
* TINKERPOP-1963 Use of reducing step in choose()
* TINKERPOP-1972 inject() tests are throwing exceptions in .NET GLV tests
* TINKERPOP-1978 Check for Websocket connection state when retrieved from Connection Pool missing
* TINKERPOP-1979 Several OLAP issues in MathStep
* TINKERPOP-1988 minor error in documentation
* TINKERPOP-1999 [Java][gremlin-driver] Query to a remote server via the websocket client hangs indefinitely if the server becomes unavailable
* TINKERPOP-2005 Intermittent NullPointerException in response handling
* TINKERPOP-2009 Pick.any and Pick.none should be exposed in Gremlin-JavaScript
* TINKERPOP-2021 Prevent maximum recursion depth failure
* TINKERPOP-2030 KeepAlive task executed for every Connection.write call
* TINKERPOP-2032 Update jython-standalone
* TINKERPOP-2044 Cannot reconnect to Azure cosmos host that becomes available again

==== Improvements

* TINKERPOP-1113 GraphComputer subclasses should support native methods
* TINKERPOP-1365 Log the seed used to initialize Random in tests
* TINKERPOP-1447 Add some JavaScript intelligence to the documentation so that comments and output are not copied in a copy paste
* TINKERPOP-1595 Go through TraversalVertexProgram with a profile and optimize.
* TINKERPOP-1778 Do not promote timedInterrupt option for Gremlin Server script processing
* TINKERPOP-1780 Add authentication tests for gremlin-python
* TINKERPOP-1836 .NET sample project
* TINKERPOP-1841 Include Python GLV tests on TravisCI
* TINKERPOP-1864 Gremlin Python tests for GraphSON 2.0 and 3.0
* TINKERPOP-1897 Provide Docker images of Gremlin Server and Console
* TINKERPOP-1945 Add support for extended GraphSon types to Gremlin.net
* TINKERPOP-1951 gremlin-server.bat doesn't support paths containing spaces
* TINKERPOP-1956 Deprecate Order incr/decr for asc/desc
* TINKERPOP-1959 Provide a way to submit scripts to the server in gremlin-javascript
* TINKERPOP-1968 Refactor elements of Gremlin Server testing
* TINKERPOP-1976 Include Computer tests for GLVs
* TINKERPOP-1977 Gremlin-JavaScript: Support SASL authentication
* TINKERPOP-1985 Update position on bulk loading
* TINKERPOP-1989 Preserve order that plugins are applied in Gremlin Console
* TINKERPOP-1995 DriverRemoteConnection close() method returns undefined
* TINKERPOP-2011 Use NumberHelper on choose()
* TINKERPOP-2012 Target .NET Standard 2.0 for Gremlin.Net
* TINKERPOP-2015 Allow users to configure the WebSocket connections
* TINKERPOP-2016 Upgrade Jackson FasterXML to 2.9.5 or later to fix security vulnerability
* TINKERPOP-2017 Check for Column in by()
* TINKERPOP-2022 Cluster SSL should trust default ca certs by default
* TINKERPOP-2023 Gremlin Server should not create self-signed certs *(breaking)*
* TINKERPOP-2024 Gremlin Server Application archetype should connect via withRemote
* TINKERPOP-2025 Change to SHA-256/512 and drop SHA-1 for releases
* TINKERPOP-2026 Gremlin.Net.Driver should check ClientWebSocket.State before closing
* TINKERPOP-2034 Register synchronizedMap() with Gryo
* TINKERPOP-2035 Gremlin-JavaScript: Pass custom headers to the websocket connection
* TINKERPOP-2040 Improve flexibility of GroovyTranslator to handle custom types
* TINKERPOP-2045 Remove non-indy groovy dependencies
* TINKERPOP-2055 Provide support for special number cases like Infinity in GraphSON
* TINKERPOP-2056 Use NumberHelper in Compare

[[release-3-3-3]]
=== TinkerPop 3.3.3 (Release Date: May 8, 2018)

This release also includes changes from <<release-3-2-9, 3.2.9>>.

* Implemented `TraversalSelectStep` which allows to `select()` runtime-generated keys.
* Coerced `BulkSet` to `g:List` in GraphSON 3.0.
* Deprecated `CredentialsGraph` DSL in favor of `CredentialsTraversalDsl` which uses the recommended method for Gremlin DSL development.
* Allowed `iterate()` to be called after `profile()`.

==== Bugs

* TINKERPOP-1869 Profile step and iterate do not play nicely with each other
* TINKERPOP-1927 Gherkin scenario expects list with duplicates, but receives g:Set
* TINKERPOP-1947 Path history isn't preserved for keys in mutations

==== Improvements

* TINKERPOP-1628 Implement TraversalSelectStep
* TINKERPOP-1755 No docs for ReferenceElements
* TINKERPOP-1903 Credentials DSL should use the Java annotation processor
* TINKERPOP-1912 Remove MD5 checksums
* TINKERPOP-1934 Bump to latest version of httpclient
* TINKERPOP-1936 Performance enhancement to Bytecode deserialization
* TINKERPOP-1943 JavaScript GLV: Support GraphSON3
* TINKERPOP-1944 JavaScript GLV: DriverRemoteConnection is not exported in the root module
* TINKERPOP-1950 Traversal construction performance enhancements
* TINKERPOP-1953 Bump to Groovy 2.4.15

[[release-3-3-2]]
=== TinkerPop 3.3.2 (Release Date: April 2, 2018)

This release also includes changes from <<release-3-2-8, 3.2.8>>.

* Fixed regression issue where the HTTPChannelizer doesn't instantiate the specified AuthenticationHandler.
* Defaulted GLV tests for gremlin-python to run for GraphSON 3.0.
* Fixed a bug with `Tree` serialization in GraphSON 3.0.
* In gremlin-python, the GraphSON 3.0 `g:Set` type is now deserialized to `List`.

==== Bugs

* TINKERPOP-1053 installed plugins are placed in a directory relative to where gremlin.sh is started
* TINKERPOP-1509 Failing test case for tree serialization
* TINKERPOP-1738 Proper functioning of GraphSONReader depends on order of elements in String representation
* TINKERPOP-1758 RemoteStrategy should be before all other DecorationStrategies.
* TINKERPOP-1855 Update Rexster links
* TINKERPOP-1858 HttpChannelizer regression: Does not create specified AuthenticationHandler
* TINKERPOP-1859 Complex instance of P not serializing to bytecode properly
* TINKERPOP-1860 valueMap(True) result in error in gremlin-python
* TINKERPOP-1862 TinkerGraph VertexProgram message passing doesn't work properly when using Direction.BOTH
* TINKERPOP-1867 union() can produce extra traversers
* TINKERPOP-1872 Apply edgeFunction in SparkMessenger
* TINKERPOP-1873 min() and max() work only in the range of Integer values
* TINKERPOP-1874 P does not appear to be serialized consistently in GraphSON
* TINKERPOP-1875 Gremlin-Python only aggregates to list when using GraphSON3
* TINKERPOP-1879 Gremlin Console does not resepect equal sign for flag argument assignments
* TINKERPOP-1880 Gremlin.NET Strong name signature could not be verified. (HRESULT: 0x80131045)
* TINKERPOP-1883 gremlinpython future will never return
* TINKERPOP-1890 getAnonymousTraversalClass() is not being generated for Java DSLs
* TINKERPOP-1891 Serialization of P.not() for gremlin-javascript
* TINKERPOP-1892 GLV test failures for .NET
* TINKERPOP-1894 GraphSONMessageSerializerV2d0 fails to deserialize valid P.not()
* TINKERPOP-1896 gremlin-python lambdas error
* TINKERPOP-1907 Fix failing GLV test for withSack() in .NET
* TINKERPOP-1917 gx:BigDecimal serialization broken in Gremlin.Net on systems with ',' as decimal separator
* TINKERPOP-1918 Scenarios fail because of wrong numerical types
* TINKERPOP-1919 Gherkin runner doesn't work with P.And() and P.Or() in Gremlin.Net
* TINKERPOP-1920 Tests fail because P.Within() arguments are wrapped in an array in Gremlin.Net
* TINKERPOP-1922 Gherkin features fail that contain P.not() in Gremlin.Net

==== Improvements

* TINKERPOP-1357 Centrality Recipes should mention pageRank and OLAP.
* TINKERPOP-1489 Provide a Javascript Gremlin Language Variant
* TINKERPOP-1586 SubgraphStrategy in OLAP
* TINKERPOP-1726 Support WebSockets ping/pong keep-alive in Gremlin server
* TINKERPOP-1842 iterate() missing in terminal steps documentation
* TINKERPOP-1844 Python GLV test should run for GraphSON 3.0 *(breaking)*
* TINKERPOP-1850 Range step has undocumented special values
* TINKERPOP-1854 Support lambdas in Gremlin.Net
* TINKERPOP-1857 GLV test suite consistency and completeness
* TINKERPOP-1863 Delaying the setting of requestId till the RequestMessage instantiation time
* TINKERPOP-1865 Run Gremlin .NET GLV tests with GraphSON 3.0
* TINKERPOP-1866 Support g:T for .NET
* TINKERPOP-1868 Support inject source step in Gremlin.Net
* TINKERPOP-1870 n^2 synchronious operation in OLAP WorkerExecutor.execute() method
* TINKERPOP-1871 Exception handling is slow in element  ReferenceElement creation
* TINKERPOP-1877 Add new graph data for specialized testing scenarios
* TINKERPOP-1884 Bump to Netty 4.0.56.Final
* TINKERPOP-1885 Various Gremlin.Net documentation updates
* TINKERPOP-1901 Enable usage of enums in more steps in Gremlin.Net
* TINKERPOP-1908 Bump to Groovy 2.4.14
* TINKERPOP-1911 Refactor JavaTranslator to cache all reflective calls
* TINKERPOP-1914 Support construct a GremlinServer instance from gremlin executor service

[[release-3-3-1]]
=== TinkerPop 3.3.1 (Release Date: December 17, 2017)

This release also includes changes from <<release-3-2-7, 3.2.7>>.

* Added `NoneStep` and `Traversal.none()` for full filtering integration with `iterate()`.
* Fixed bug in serialization of `Path` for GraphSON 3.0 in `gremlin-python`.
* Added support for GraphSON 3.0 in Gremlin.Net.
* Added `math()`-step which supports scientific calculator capabilities for numbers within a traversal.
* Added missing `GraphTraversalSource.addE()`-method to `GremlinDslProcessor`.
* Changed `to()` and `from()` traversal-based steps to take a wildcard `?` instead of of `E`.
* Added `addV(traversal)` and `addE(traversal)` so that created element labels can be determined dynamically.
* `PageRankVertexProgram` supports `maxIterations` but will break out early if epsilon-based convergence occurs.
* Added support for epsilon-based convergence in `PageRankVertexProgram`.
* Fixed two major bugs in how PageRank was being calculated in `PageRankVertexProgram`.
* Added `Io.requiresVersion(Object)` to allow graph providers a way to check the `Io` type and version being constructed.
* Defaulted `IoCore.gryo()` and `IoCore.graphson()` to both use their 3.0 formats which means that `Graph.io()` will use those by default.
* Bumped Neo4j 3.2.3

==== Bugs

* TINKERPOP-1773 Lop should be created as a "software" and not a "person"
* TINKERPOP-1783 PageRank gives incorrect results for graphs with sinks *(breaking)*
* TINKERPOP-1799 Failure to serialize path() in gremlin-python
* TINKERPOP-1847 tinkergraph-gremlin dependency on gremlin-test, bad scope?

==== Improvements

* TINKERPOP-1632 Create a set of default functions
* TINKERPOP-1692 Bump to Neo4j 3.2.3
* TINKERPOP-1717 Update name and link of DynamoDB storage backend in landing page
* TINKERPOP-1730 Gremlin .NET support for GraphSON 3.0
* TINKERPOP-1767 Method for graph providers to check an IO version and type
* TINKERPOP-1793 addE() should allow dynamic edge labels
* TINKERPOP-1834 Consider iterate() as a first class step

[[release-3-3-0]]
=== TinkerPop 3.3.0 (Release Date: August 21, 2017)

This release also includes changes from <<release-3-2-6, 3.2.6>>.

* Removed previously deprecated `ScriptElementFactory`.
* Added `GraphTraversalSource.addE(String)` in support of `g.addE().from().to()`.
* Added support for `to(Vertex)` and `from(Vertex)` as a shorthand for `to(V(a))` and `from(V(b))`.
* Bumped to support Spark 2.2.0.
* Detected if type checking was required in `GremlinGroovyScriptEngine` and disabled related infrastructure if not.
* Removed previously deprecated `GraphTraversal.selectV3d0()` step.
* Removed previously deprecated `DetachedEdge(Object,String,Map,Pair,Pair)` constructor.
* Removed previously deprecated `Bindings` constructor. It is now a private constructor.
* Removed previously deprecated `TraversalSource.withBindings()`.
* Removed previously deprecated `GraphTraversal.sack(BiFunction,String)`.
* `TraversalMetrics` and `Metrics` Gryo 1.0 formats changed given internal changes to their implementations.
* Made `TraversalMetrics` safe to write to from multiple threads.
* Removed previously deprecated `TraversalSideEffects` methods.
* Removed previously deprecated `finalization.LazyBarrierStrategy` (moved to `optimization.LazyBarrierStrategy`).
* Removed previously deprecated `Constants` in Hadoop.
* Removed previously deprecated `VertexComputing.generateComputer(Graph)`.
* Removed previously deprecated `ConfigurationTraversal`.
* Established the Gryo 3.0 format.
* `GryoVersion` now includes a default `ClassResolver` to supply to the `GryoMapper`.
* `GryoClassResolver` renamed to `GryoClassResolverV1d0` which has an abstract class that for providers to extend in `AbstractGryoClassResolver`.
* Removed previously deprecated `Order` enums of `keyIncr`, `keyDecr`, `valueIncr`, and `valueDecr.`
* Removed previously deprecated `GraphTraversal.mapKeys()` step.
* Removed previously deprecated `GraphTraversal.mapValues()` step.
* Removed previously deprecated `GraphTraversal#addV(Object...)`.
* Removed previously deprecated `GraphTraversal#addE(Direction, String, String, Object...)`.
* Removed previously deprecated `GraphTraversal#addOutE(String, String, Object...)`.
* Removed previously deprecated `GraphTraversal#addInV(String, String, Object...)`.
* Removed previously deprecated `GraphTraversal.groupV3d0()` and respective `GroupSideEffectStepV3d0` and `GroupStepV3d0`.
* Removed previously deprecated `TraversalSource.Builder` class.
* Removed previously deprecated `ConnectiveP`, `AndP`, `OrP` constructors.
* Removed previously deprecated `TraversalScriptFunction` class.
* Removed previously deprecated `TraversalScriptHelper` class.
* Removed previously deprecated `ScriptEngineCache` class.
* Removed previously deprecated `CoreImports` class.
* Removed previously deprecated `GremlinJythonScriptEngine#()` constructor.
* Removed access to previously deprecated `CoreGremlinPlugin#INSTANCE` field.
* `gremlin.sh` and `gremln.bat` no longer support the option to pass a script as an argument for execution mode without using the `-i` option.
* Graphite and Ganglia are no longer packaged with the Gremlin Server distribution.
* `TransactionException` is no longer a class of `AbstractTransaction` and it extends `RuntimeException`.
* Included an ellipse on long property names that are truncated.
* Renamed `RangeByIsCountStrategy` to `CountStrategy`.
* Added more specific typing to various `__` traversal steps. E.g. `<A,Vertex>out()` is `<Vertex,Vertex>out()`.
* Updated Docker build scripts to include Python dependencies (NOTE: users should remove any previously generated TinkerPop Docker images).
* Added "attachment requisite" `VertexProperty.element()` and `Property.element()` data in GraphSON serialization.
* GraphSON 3.0 is now the default serialization format in TinkerGraph and Gremlin Server.
* Changed `ServerGremlinExecutor` to not use generics since there really is no flexibility in the kind of `ScheduledExecutorService` that will be used.
* Removed support for passing a byte array on the `sasl` parameter.
* Removed previously deprecated `GraphSONMapper$Builder#embedTypes` option.
* Removed previously deprecated `:remote config timeout max`.
* Removed previously deprecated `ConnectionPoolSettings.sessionId` and `ConnectionPoolSettings.optionalSessionId()`.
* Removed previously deprecated `reconnectInitialDelay` setting from the Java driver.
* Removed previously deprecated `useMapperFromGraph` option.
* Established the GraphSON 3.0 format with new `g:Map`, `g:List` and `g:Set` types.
* Removed previously deprecated `Io.Builder#registry(IoRegistry)` method.
* Removed previously deprecated `GryoMessageSerializerV1d0(GryoMapper)` constructor.
* Removed previously deprecated `TinkerIoRegistry`.
* Removed previously deprecated `getInstance()` methods on all TinkerPop classes.
* Removed previously deprecated `VertexPropertyFeatures.supportsAddProperty()`.
* Removed previously deprecated TinkerGraph configuration member variables.
* Removed previously deprecated `Transaction.submit(Function)`.
* Removed previously deprecated `OpSelectorHandler.errorMeter` and `AbstractEvalOpProcessor.errorMeter` fields.
* Removed previously deprecated `AbstractEvalOpProcessor.validBindingName` field.
* Removed previously deprecated `SimpleAuthenticator.CONFIG_CREDENTIALS_LOCATION` field.
* Removed previously deprecated `IteratorHandler`, `NioGremlinResponseEncoder` and `WsGremlinResponseEncoder` classes.
* Removed previously deprecated `Session.kill()` and `Session.manualKill()`.
* Removed previously deprecated `Authenticator.newSaslNegotiator()` and its method implementations in classes that were assignable to that interface.
* Removed `gremlin-groovy-test`.
* Removed previously deprecated "G" functions in `gremlin-groovy` (i.e. `GFunction`).
* Removed references to the old `GremlinPlugin` system that was in `gremlin-groovy` - the revised `GremlinPlugin` system in `gremlin-core` is the only one now in use.
* `GremlinGroovyScriptEngine` no longer implements the now removed `DependencyManager`.
* Added `Vertex`, `Edge`, `VertexProperty`, and `Property` serializers to Gremlin-Python and exposed tests that use graph object arguments.
* `Bytecode.getSourceInstructions()` and `Bytecode.getStepInstructions()` now returns `List<Instruction>` instead of `Iterable<Instruction>`.
* Added various `TraversalStrategy` registrations with `GryoMapper`.
* Fixed a naming mistake in Gremlin-Python: `IdentityRemoveStrategy` is now called `IdentityRemovalStrategy`.
* Added `TranslationStrategy` test infrastructure that verifies `Bytecode` generated from a translation is equal to the original `Bytecode`.
* Moved `NumberHelper` into the `org.apache.tinkerpop.gremlin.util` package.
* Added `Pop.mixed` instead of using `null` to represent such semantics.
* `select()`-step now defaults to using `Pop.last` instead of `Pop.mixed`.
* Added `gremlin-io-test` module to validate IO formats.
* `RequestMessage` and `ResponseMessage` are now registered with `GryoMapper` as part of the TinkerPop range of type identifiers.
* Removed previously deprecated `Console` constructor that took a `String` as an argument from `gremlin-console`.
* Removed previously deprecated `ConcurrentBindings` from `gremlin-groovy`.
* Removed previously deprecated `ScriptExecutor` from `gremlin-groovy`.
* Removed previously deprecated `SandboxExtension` from `gremlin-groovy`.
* Removed previously deprecated `GremlinGroovyScriptEngine` constructor that took `ImportCustomizerProvider` as an argument from `gremlin-groovy`.
* Removed previously deprecated `GremlinGroovyScriptEngine#plugins()` from `gremlin-groovy`.
* Added `OptionalStep` for use with `optional()` to better handle issues associated with branch side-effects.
* `UnfoldStep` now supports unfolding of arrays.
* Removed all performance tests that were not part of `gremlin-benchmark`.
* Removed dependency on `junit-benchmarks` and it's related reference to `h2`.
* Moved the source for the "home page" into the repository under `/site` so that it easier to accept contributions.
* Added `UnshadedKryoShimService` as the new default serializer model for `SparkGraphComputer`.
* `GryoRegistrator` is more efficient than the previous `GryoSerializer` model in `SparkGraphComputer`.
* Added support for `IoRegistry` custom serialization in Spark/Giraph and provided a general `hadoop-gremlin` test suite.
* Replaced term `REST` with `HTTP` to remove any confusion as to the design of the API.
* Moved `gremlin-benchmark` under `gremlin-tools` module.
* Added `gremlin-tools` and its submodule `gremlin-coverage`.
* Removed `tryRandomCommit()` from `AbstractGremlinTest`.
* Changed `gremlin-benchmark` system property for the report location to `benchmarkReportDir` for consistency.
* Added SysV and systemd init scripts.
* `GraphTraversal.valueMap(includeTokens,propertyKeys...)` now returns a `Map<Object,E>` since keys could be `T.id` or `T.label`.
* Added `skip(long)` and `skip((Scope,long)` which call the `range(low,high)` equivalents with -1 as the high.
* Added Kerberos authentication to `gremlin-server` for websockets and nio transport.
* Added audit logging of authenticated users and gremlin queries to `gremlin-server`.

==== Bugs

* TINKERPOP-1211 UnfoldStep should unfold arrays. *(breaking)*
* TINKERPOP-1426 GryoSerializer should implement Java serialization interface
* TINKERPOP-1465 Remove deprecated newSaslNegotiator *(breaking)*
* TINKERPOP-1483 PropertyMapStep returns Map<String,E> but puts non String keys in it!
* TINKERPOP-1520 Difference between 'has' step generated graphson2.0 in java and python glv implementation
* TINKERPOP-1533 Storage and IoRegistry
* TINKERPOP-1597 PathRetractionStrategy messing up certain traversals
* TINKERPOP-1635 gremlin-python: Duplicate serialization of element property in PropertySerializer
* TINKERPOP-1658 Graphson2 map keys are serialised as strings
* TINKERPOP-1716 Traversal strategies are not applied with remote in Gremlin Console

==== Improvements

* TINKERPOP-832 Remove deprecated addV/E/InE/OutE methods *(breaking)*
* TINKERPOP-833 Remove deprecated GremlinGroovyScriptEngine constructor and plugins() *(breaking)*
* TINKERPOP-834 Remove deprecated sack() method *(breaking)*
* TINKERPOP-880 Remove deprecated GroupStepV3d0 and GroupSideEffectStepV3d0 *(breaking)*
* TINKERPOP-929 Remove Deprecated TinkerGraph public static methods. *(breaking)*
* TINKERPOP-980 Add a service script or daemon mode in the distribution *(breaking)*
* TINKERPOP-999 ServerGremlinExecutor construction need not use generics for ExecutorService *(breaking)*
* TINKERPOP-1004 Make Transaction.commit() failures consistent across implementations. *(breaking)*
* TINKERPOP-1010 Remove deprecated credentialsDbLocation for SimpleAuthenticator *(breaking)*
* TINKERPOP-1024 Remove deprecated tryRandomCommit() *(breaking)*
* TINKERPOP-1028 Remove deprecated ConnectionPoolSettings session settings *(breaking)*
* TINKERPOP-1040 Remove deprecated SandboxExtension *(breaking)*
* TINKERPOP-1046 Remove deprecated Gremlin Server handler implementations *(breaking)*
* TINKERPOP-1049 Remove deprecated error meter member variables in Gremlin Server handlers *(breaking)*
* TINKERPOP-1094 Remove deprecated VertexPropertyFeatures.FEATURE_ADD_PROPERTY *(breaking)*
* TINKERPOP-1116 Some anonymous traversal steps can be hard typed. *(breaking)*
* TINKERPOP-1130 Each release should store Kryo/GraphSON/GraphML versions to ensure future compatibility *(breaking)*
* TINKERPOP-1142 Remove deprecated valueIncr, valueDecr, keyIncr, keyDecr. *(breaking)*
* TINKERPOP-1169 Remove deprecated TraversalScriptFunction and TraversalScriptHelper *(breaking)*
* TINKERPOP-1170 Remove deprecated ConfigurationTraversal. *(breaking)*
* TINKERPOP-1171 Remove deprecated TraversalSource.Builder *(breaking)*
* TINKERPOP-1235 Remove deprecated ProcessPerformanceSuite and TraversalPerformanceTest *(breaking)*
* TINKERPOP-1275 Remove deprecated max setting for :remote *(breaking)*
* TINKERPOP-1283 Remove deprecated ScriptExecutor *(breaking)*
* TINKERPOP-1289 Remove deprecated ConnectiveP, AndP, and OrP constructors. *(breaking)*
* TINKERPOP-1291 Remove deprecated mapValues and mapKeys methods *(breaking)*
* TINKERPOP-1313 Rename RangeByIsCountStrategy *(breaking)*
* TINKERPOP-1316 Remove deprecated constructor from GryoMessageSerializers *(breaking)*
* TINKERPOP-1327 Bring GryoRegistrator to the forefront and deprecate GryoSerializer *(breaking)*
* TINKERPOP-1363 Cleanup Docker build script for next major release *(breaking)*
* TINKERPOP-1369 Replace REST API with HTTP API
* TINKERPOP-1389 Support Spark 2.0.0
* TINKERPOP-1399 NumberHelper needs to go into util and have a private constructor *(breaking)*
* TINKERPOP-1404 Path/label optimization
* TINKERPOP-1408 Remove Deprecated Io.Builder.registry() *(breaking)*
* TINKERPOP-1414 Change default GraphSON version to 3.0 *(breaking)*
* TINKERPOP-1420 Remove deprecated ConcurrentBindings in gremlin-groovy *(breaking)*
* TINKERPOP-1421 Remove deprecated ControlOps *(breaking)*
* TINKERPOP-1427 GraphSON 3.0 needs collection types and consistent number typing.
* TINKERPOP-1443 Use an API checker during build
* TINKERPOP-1445 Large nested VertexProperties and Properties do not get printed well
* TINKERPOP-1454 Create Serializers for Graph objects in Gremlin-Python
* TINKERPOP-1481 Remove deprecated reconnectInitialDelay in Java driver *(breaking)*
* TINKERPOP-1485 Move source for TinkerPop site to source code repo
* TINKERPOP-1506 Optional/Coalesce should not allow sideEffect traversals.
* TINKERPOP-1514 Restructure for gremlin-tools module *(breaking)*
* TINKERPOP-1524 Bytecode.getXXXInstructions should return a List, not Iterable.
* TINKERPOP-1526 Remove deprecated Session kill() overloads *(breaking)*
* TINKERPOP-1536 Include GLVs in Docker build
* TINKERPOP-1541 Select should default to Pop.last semantics *(breaking)*
* TINKERPOP-1549 Implement skip()
* TINKERPOP-1550 Make Graphite and Ganglia optional dependencies
* TINKERPOP-1563 Remove deprecated getInstance() methods *(breaking)*
* TINKERPOP-1565 Setup GraphSON 3.0
* TINKERPOP-1566 Kerberos authentication for gremlin-server
* TINKERPOP-1574 Get rid of untyped GraphSON in 3.0
* TINKERPOP-1603 Remove support for SASL byte array in protocol *(breaking)*
* TINKERPOP-1612 Remove gremlin-groovy-test module *(breaking)*
* TINKERPOP-1621 Remove deprecated GremlnPlugin and related infrastructure *(breaking)*
* TINKERPOP-1622 Remove deprecated G functions in gremlin-groovy *(breaking)*
* TINKERPOP-1651 Remove deprecated gremlin.sh init syntax *(breaking)*
* TINKERPOP-1686 Make TraversalMetrics thread safe *(breaking)*
* TINKERPOP-1698 Gryo 3.0
* TINKERPOP-1699 Remove deprecated userMapperFromGraph *(breaking)*
* TINKERPOP-1700 Remove deprecated embedTypes option
* TINKERPOP-1706 Remove deprecated ScriptEngineCache and related dead code *(breaking)*
* TINKERPOP-1715 Bump to Spark 2.2
* TINKERPOP-1719 Remove deprecated Traversal related code *(breaking)*
* TINKERPOP-1720 Remove deprecated Hadoop code *(breaking)*
* TINKERPOP-1721 Remove deprecated Bindings related code *(breaking)*
* TINKERPOP-1724 Remove deprecated ScriptElementFactory
* TINKERPOP-1729 Remove deprecated select steps.
* TINKERPOP-1740 Add vertex parameter overload to to() and from()
* TINKERPOP-1747 Streamline inheritance for gremlin-python GraphSON serializer classes

== TinkerPop 3.2.0 (Nine Inch Gremlins)

image::https://raw.githubusercontent.com/apache/tinkerpop/master/docs/static/images/nine-inch-gremlins.png[width=185]

[[release-3-2-11]]
=== TinkerPop 3.2.11 (Release Date: January 2, 2019)

* Bumped to Jackson Databind 2.9.8

==== Improvements

* TINKERPOP-2074 Ensure that only NuGet packages for the current version are pushed
* TINKERPOP-2121 Bump Jackson Databind 2.9.8

[[release-3-2-10]]
=== TinkerPop 3.2.10 (Release Date: October 15, 2018)

* Removed conflicting non-indy groovy core dependency
* Bumped jython-standalone 2.7.1
* Added a delegate to the Gremlin.Net driver that can be used to configure the WebSocket connection.
* SSL security enhancements
* Added Gremlin version to Gremlin Server startup logging output.
* Fixed problem with Gremlin Server sometimes returning an additional message after a failure.
* Allowed spaces in classpath for `gremlin-server.bat`.
* Fixed bug in traversals that used Python lambdas with strategies in `gremlin-python`.
* Modified Maven archetype for Gremlin Server to use remote traversals rather than scripts.
* Added an system error code for failed plugin installs for Gremlin Server `-i` option.
* Fixed bug in keep-alive requests from over-queuing cancelled jobs.
* Match numbers in `choose()` options using `NumberHelper` (match values, ignore data type).
* Added support for GraphSON serialization of `Date` in Javascript.
* Added synchronized `Map` to Gryo 1.0 registrations.
* Added `Triple` to Gryo 1.0 registrations.
* Added support for `Double.NaN`, `Double.POSITIVE_INFINITY` and `Double.NEGATIVE_INFINITY`.
* Improved escaping of special characters in strings passed to the `GroovyTranslator`.
* Added `Cluster` configuration option to set a custom validation script to use to test server connectivity in the Java driver.
* Improved ability of `GroovyTranslator` to handle more types supported by GraphSON.
* Improved ability of `GroovyTranslator` to handle custom types.
* Added better internal processing of `Column` in `by(Function)`.
* Added `hasNext()` support on `Traversal` for `gremlin-python`.
* Added support for additional extended types in Gremlin.Net with `decimal`, `TimeSpan`, `BigInteger`, `byte`, `byte[]`, `char` and `short`.
* Fixed bug in Java driver where an disorderly shutdown of the server would cause the client to hang.
* Added a dotnet template project that should make it easier to get started with Gremlin.Net.
* Removed `ThreadInterruptCustomizerProvider` from documentation as a way to timeout.
* Changed behavior of `withRemote()` if called multiple times so as to simply throw an exception and not perform the side-effect of auto-closing.
* Added Docker images for Gremlin Console and Gremlin Server.
* Fixed bug in `branch()` where reducing steps as options would produce incorrect results.
* Removed recursive handling of streaming results from Gremlin-Python driver to avoid max recursion depth errors.
* Improved performance of `TraversalVertexProgram` and related infrastructure.
* Checked web socket state before closing connection in the .NET driver.
* Deprecated `BulkLoaderVertexProgram` and related infrastructure.
* Deprecated `BulkDumperVertexProgram` with the more aptly named `CloneVertexProgram`.
* Added `createGratefulDead()` to `TinkerFactory` to help make it easier to try to instantiate that toy graph.
* Added identifiers to edges in the Kitchen Sink toy graph.
* Ordered the loading of plugins in the Gremlin Console by their position in the configuration file.
* Refactored the Gremlin Server integration testing framework and streamlined that infrastructure.
* Logged the seed used in initializing `Random` for tests.
* Fixed bug in `GroovyTranslator` that didn't properly handle empty `Map` objects.
* Added concrete configuration methods to `SparkGraphComputer` to make a more clear API for configuring it.
* Fixed a bug in `TinkerGraphCountStrategy`, which didn't consider that certain map steps may not emit an element.
* Fixed a bug in JavaScript GLV where DriverRemoteConnection close() method didn't returned a Promise instance.
* Bumped to Jackson 2.9.6.
* Sasl Plain Text Authentication added to Gremlin Javascript.
* Ability to send scripts to server added to Gremlin Javascript.
* Translator class added to Gremlin Javascript to translate bytecode to script clientside.

==== Bugs

* TINKERPOP-1898 Issue with bindings in strategies and lambdas
* TINKERPOP-1933 gremlin-python maximum recursion depth exceeded on large responses
* TINKERPOP-1958 TinkerGraphCountStrategy can return wrong counts
* TINKERPOP-1961 Duplicate copies of images directory in docs
* TINKERPOP-1962 GroovyTranslator doesn't handle empty maps
* TINKERPOP-1963 Use of reducing step in choose()
* TINKERPOP-1972 inject() tests are throwing exceptions in .NET GLV tests
* TINKERPOP-1978 Check for Websocket connection state when retrieved from Connection Pool missing
* TINKERPOP-1988 minor error in documentation
* TINKERPOP-1999 [Java][gremlin-driver] Query to a remote server via the websocket client hangs indefinitely if the server becomes unavailable
* TINKERPOP-2005 Intermittent NullPointerException in response handling
* TINKERPOP-2009 Pick.any and Pick.none should be exposed in Gremlin-JavaScript
* TINKERPOP-2030 KeepAlive task executed for every Connection.write call
* TINKERPOP-2032 Update jython-standalone
* TINKERPOP-2044 Cannot reconnect to Azure cosmos host that becomes available again

==== Improvements

* TINKERPOP-1113 GraphComputer subclasses should support native methods
* TINKERPOP-1365 Log the seed used to initialize Random in tests
* TINKERPOP-1595 Go through TraversalVertexProgram with a profile and optimize.
* TINKERPOP-1778 Do not promote timedInterrupt option for Gremlin Server script processing
* TINKERPOP-1780 Add authentication tests for gremlin-python
* TINKERPOP-1836 .NET sample project
* TINKERPOP-1841 Include Python GLV tests on TravisCI
* TINKERPOP-1897 Provide Docker images of Gremlin Server and Console
* TINKERPOP-1945 Add support for extended GraphSon types to Gremlin.net
* TINKERPOP-1951 gremlin-server.bat doesn't support paths containing spaces
* TINKERPOP-1959 Provide a way to submit scripts to the server in gremlin-javascript
* TINKERPOP-1968 Refactor elements of Gremlin Server testing
* TINKERPOP-1976 Include Computer tests for GLVs
* TINKERPOP-1977 Gremlin-JavaScript: Support SASL authentication
* TINKERPOP-1985 Update position on bulk loading
* TINKERPOP-1989 Preserve order that plugins are applied in Gremlin Console
* TINKERPOP-1995 DriverRemoteConnection close() method returns undefined
* TINKERPOP-2011 Use NumberHelper on choose()
* TINKERPOP-2012 Target .NET Standard 2.0 for Gremlin.Net
* TINKERPOP-2015 Allow users to configure the WebSocket connections
* TINKERPOP-2016 Upgrade Jackson FasterXML to 2.9.5 or later to fix security vulnerability
* TINKERPOP-2017 Check for Column in by()
* TINKERPOP-2022 Cluster SSL should trust default ca certs by default
* TINKERPOP-2023 Gremlin Server should not create self-signed certs *(breaking)*
* TINKERPOP-2024 Gremlin Server Application archetype should connect via withRemote
* TINKERPOP-2025 Change to SHA-256/512 and drop SHA-1 for releases
* TINKERPOP-2026 Gremlin.Net.Driver should check ClientWebSocket.State before closing
* TINKERPOP-2034 Register synchronizedMap() with Gryo
* TINKERPOP-2035 Gremlin-JavaScript: Pass custom headers to the websocket connection
* TINKERPOP-2040 Improve flexibility of GroovyTranslator to handle custom types
* TINKERPOP-2045 Remove non-indy groovy dependencies
* TINKERPOP-2055 Provide support for special number cases like Infinity in GraphSON
* TINKERPOP-2056 Use NumberHelper in Compare

[[release-3-2-9]]
=== TinkerPop 3.2.9 (Release Date: May 8, 2018)

* Fixed bug where path history was not being preserved for keys in mutations.
* Bumped to httpclient 4.5.5.
* Bumped to Groovy 2.4.15 - fixes bug with `Lambda` construction.
* Improved performance of GraphSON deserialization of `Bytecode`.
* Improved performance of traversal construction.

====  Bugs

* TINKERPOP-1947 Path history isn't preserved for keys in mutations

==== Improvements

* TINKERPOP-1755 No docs for ReferenceElements
* TINKERPOP-1912 Remove MD5 checksums
* TINKERPOP-1934 Bump to latest version of httpclient
* TINKERPOP-1936 Performance enhancement to Bytecode deserialization
* TINKERPOP-1944 JavaScript GLV: DriverRemoteConnection is not exported in the root module
* TINKERPOP-1950 Traversal construction performance enhancements
* TINKERPOP-1953 Bump to Groovy 2.4.15

[[release-3-2-8]]
=== TinkerPop 3.2.8 (Release Date: April 2, 2018)

* Added a `Lambda` class to Gremlin.Net that makes it possible to use Groovy and Python lambdas with Gremlin.Net.
* Enums are now represented as classes in Gremlin.Net which allows to use them as arguments in more steps.
* Bumped to Groovy 2.4.14.
* Added `checkAdjacentVertices` option to `SubgraphStrategy`.
* Modified `GremlinDslProcessor` so that it generated the `getAnonymousTraversalClass()` method to return the DSL version of `__`.
* Added the "Kitchen Sink" test data set.
* Fixed deserialization of `P.not()` for GraphSON.
* Bumped to Jackson 2.9.4.
* Improved performance of `JavaTranslator` by caching reflected methods required for traversal construction.
* Ensure that `RemoteStrategy` is applied before all other `DecorationStrategy` instances.
* Added `idleConnectionTimeout` and `keepAliveInterval` to Gremlin Server that enables a "ping" and auto-close for seemingly dead clients.
* Fixed a bug where lambdas in `gremlin-python` would trigger a failure if steps using python-only symbols were present (such as `as_()`).
* Fixed a bug in `NumberHelper` that led to wrong min/max results if numbers exceeded the Integer limits.
* Delayed setting of the request identifier until `RequestMessage` construction by the builder.
* `ReferenceElement` avoids `UnsupportedOperationException` handling in construction thus improving performance.
* Improved error messaging for failed serialization and deserialization of request/response messages.
* Fixed handling of `Direction.BOTH` in `Messenger` implementations to pass the message to the opposite side of the `StarGraph`.
* Removed hardcoded expectation in metrics serialization test suite as different providers may have different outputs.
* Added `IndexedTraverserSet` which indexes on the value of a `Traverser` thus improving performance when used.
* Utilized `IndexedTraverserSet` in `TraversalVertexProgram` to avoid extra iteration when doing `Vertex` lookups.
* Bumped to Netty 4.0.56.Final.
* Fixed .NET GraphSON serialization of `P.Within()` and `P.without()` when passing a `Collection` as an argument.
* Fixed a bug in Gremlin Console which prevented handling of `gremlin.sh` flags that had an "=" between the flag and its arguments.
* Fixed bug where `SparkMessenger` was not applying the `edgeFunction` from `MessageScope`.
* Fixed a bug in `ComputerAwareStep` that didn't handle `reset()` properly and thus occasionally produced some extra traversers.
* Removed `TraversalPredicate` class in Gremlin.Net. It is now included in the `P` class instead.

==== Bugs

* TINKERPOP-1053 installed plugins are placed in a directory relative to where gremlin.sh is started
* TINKERPOP-1509 Failing test case for tree serialization
* TINKERPOP-1738 Proper functioning of GraphSONReader depends on order of elements in String representation
* TINKERPOP-1758 RemoteStrategy should be before all other DecorationStrategies.
* TINKERPOP-1855 Update Rexster links
* TINKERPOP-1859 Complex instance of P not serializing to bytecode properly
* TINKERPOP-1860 valueMap(True) result in error in gremlin-python
* TINKERPOP-1862 TinkerGraph VertexProgram message passing doesn't work properly when using Direction.BOTH
* TINKERPOP-1867 union() can produce extra traversers
* TINKERPOP-1872 Apply edgeFunction in SparkMessenger
* TINKERPOP-1873 min() and max() work only in the range of Integer values
* TINKERPOP-1874 P does not appear to be serialized consistently in GraphSON
* TINKERPOP-1879 Gremlin Console does not resepect equal sign for flag argument assignments
* TINKERPOP-1880 Gremlin.NET Strong name signature could not be verified. (HRESULT: 0x80131045)
* TINKERPOP-1883 gremlinpython future will never return
* TINKERPOP-1890 getAnonymousTraversalClass() is not being generated for Java DSLs
* TINKERPOP-1891 Serialization of P.not() for gremlin-javascript
* TINKERPOP-1892 GLV test failures for .NET
* TINKERPOP-1894 GraphSONMessageSerializerV2d0 fails to deserialize valid P.not()
* TINKERPOP-1896 gremlin-python lambdas error
* TINKERPOP-1907 Fix failing GLV test for withSack() in .NET
* TINKERPOP-1917 gx:BigDecimal serialization broken in Gremlin.Net on systems with ',' as decimal separator
* TINKERPOP-1918 Scenarios fail because of wrong numerical types
* TINKERPOP-1919 Gherkin runner doesn't work with P.And() and P.Or() in Gremlin.Net
* TINKERPOP-1920 Tests fail because P.Within() arguments are wrapped in an array in Gremlin.Net
* TINKERPOP-1922 Gherkin features fail that contain P.not() in Gremlin.Net

==== Improvements

* TINKERPOP-1357 Centrality Recipes should mention pageRank and OLAP.
* TINKERPOP-1489 Provide a Javascript Gremlin Language Variant
* TINKERPOP-1586 SubgraphStrategy in OLAP
* TINKERPOP-1726 Support WebSockets ping/pong keep-alive in Gremlin server
* TINKERPOP-1842 iterate() missing in terminal steps documentation
* TINKERPOP-1850 Range step has undocumented special values
* TINKERPOP-1854 Support lambdas in Gremlin.Net
* TINKERPOP-1857 GLV test suite consistency and completeness
* TINKERPOP-1863 Delaying the setting of requestId till the RequestMessage instantiation time
* TINKERPOP-1868 Support inject source step in Gremlin.Net
* TINKERPOP-1870 n^2 synchronious operation in OLAP WorkerExecutor.execute() method
* TINKERPOP-1877 Add new graph data for specialized testing scenarios
* TINKERPOP-1884 Bump to Netty 4.0.56.Final
* TINKERPOP-1885 Various Gremlin.Net documentation updates
* TINKERPOP-1901 Enable usage of enums in more steps in Gremlin.Net
* TINKERPOP-1908 Bump to Groovy 2.4.14
* TINKERPOP-1911 Refactor JavaTranslator to cache all reflective calls

[[release-3-2-7]]
=== TinkerPop 3.2.7 (Release Date: December 17, 2017)

* Added core GraphSON classes for Gremlin-Python: `UUID`, `Date`, and `Timestamp`.
* Documented the recommended method for constructing DSLs with Gremlin.Net.
* Provided a method to configure detachment options with `EventStrategy`.
* Fixed a race condition in `TinkerIndex`.
* Fixed bug in handling of the long forms of `-e` and `-i` (`--execute` and `--interactive` respectively) for Gremlin Console.
* Fixed bug in `LambdaRestrictionStrategy` where traversals using `Lambda` scripts weren't causing the strategy to trigger.
* Improved error messaging for bytecode deserialization errors in Gremlin Server.
* Fixed an `ArrayOutOfBoundsException` in `hasId()` for the rare situation when the provided collection is empty.
* Bumped to Netty 4.0.53
* `TraversalVertexProgram` `profile()` now accounts for worker iteration in `GraphComputer` OLAP.
* Returned the `Builder` instance from the `DetachedEdge.Builder` methods of `setOutE` and `setOutV`.
* Added test framework for GLVs.
* Fixed bug in `TraversalHelper.replaceStep()` where the step being replaced needed to be removed prior to the new one being added.
* Added alias support in the .NET `DriverRemoteConnection`.
* Added a test for self-edges and fixed `Neo4jVertex` to provided repeated self-edges on `BOTH`.
* Better respected permissions on the `plugins.txt` file and prevented writing if marked as read-only.
* Added getters for the lambdas held by `LambdaCollectingBarrierStep`, `LambdaFlatMapStep` and `LambdaSideEffectStep`.
* Fixed an old hack in `GroovyTranslator` and `PythonTranslator` where `Elements` were being mapped to their id only.
* Fixed an "attachement"-bug in `InjectStep` with a solution generalized to `StartStep`.
* Truncate the script in error logs and error return messages for "Method code too large" errors in Gremlin Server.
* Fixed a bug in `LambdaRestrictionStrategy` where it was too eager to consider a step as being a lambda step.
* `ReferenceVertex` was missing its `label()` string. `ReferenceElement` now supports all label handling.
* Fixed a bug where bytecode containing lambdas would randomly select a traversal source from bindings.
* Deprecated `GremlinScriptEngine.eval()` methods and replaced them with new overloads that include the specific `TraversalSource` to bind to.
* Added `GraphHelper.cloneElements(Graph original, Graph clone)` to the `gremlin-test` module to quickly clone a graph.
* Added `GremlinDsl.AnonymousMethod` annotation to help provide explicit types for anonymous methods when the types are not easily inferred.
* Bumped to GMavenPlus 1.6.
* Added better error message for illegal use of `repeat()`-step.
* Fixed a bug in `RangeByIsCountStrategy` that led to unexpected behaviors when predicates were used with floating point numbers.
* Bumped to Jackson 2.8.10.
* Deprecated `MutationListener.vertexPropertyChanged()` method that did not use `VertexProperty` and added a new method that does.
* Added an `EmbeddedRemoteConnection` so that it's possible to mimic a remote connection within the same JVM.
* Supported interruption for remote traversals.
* Allow the `:remote` command to accept a `Cluster` object defined in the console itself.
* The Console's `plugin.txt` file is only updated if there were manually uninstalled plugins.
* Fixed a bug in `MatchStep` where mid-traversal `where()` variables were not being considered in start-scope.
* Generalized `MatchStep` to locally compute all clauses with barriers (not just reducing barriers).
* Ensured that plugins were applied in the order they were configured.
* Fixed a bug in `Neo4jGremlinPlugin` that prevented it from loading properly in the `GremlinPythonScriptEngine`.
* Fixed a bug in `ComputerVerificationStrategy` where child traversals were being analyzed prior to compilation.
* Fixed a bug that prevented Gremlin from ordering lists and streams made of mixed number types.
* Fixed a bug where `keepLabels` were being corrupted because a defensive copy was not being made when they were being set by `PathRetractionStrategy`.
* Cancel script evaluation timeout in `GremlinExecutor` when script evaluation finished.
* Added a recipe for OLAP traversals with Spark on YARN.
* Added `spark-yarn` dependencies to the manifest of `spark-gremlin`.

==== Bugs

* TINKERPOP-1650 PathRetractionStrategy makes Match steps unsolvable
* TINKERPOP-1731 Docker build does not appear to work for gremlin-dotnet
* TINKERPOP-1745 Gremlin .NET: Use DateTimeOffset instead of DateTime to represent g:Date
* TINKERPOP-1753 OrderStep not able to order by non-integer numbers
* TINKERPOP-1760 OLAP compilation failing around ConnectiveStrategy
* TINKERPOP-1761 GremlinExecutor: Timeout future not cancelled on successful script evaluation
* TINKERPOP-1762 Make MatchStep analyze mid-clause variables for executing ordering purposes.
* TINKERPOP-1764 Generalize MatchStep to localize all barriers, not just reducing barriers.
* TINKERPOP-1766 Gremlin.Net: Closed connections should not be re-used
* TINKERPOP-1782 RangeByIsCountStrategy doesn't handle floating point numbers properly
* TINKERPOP-1789 Reference elements should be represented by id and label *(breaking)*
* TINKERPOP-1790 GraphSON 3.0 doc updates
* TINKERPOP-1791 GremlinDsl custom step with generic end type produces invalid code in __.java
* TINKERPOP-1792 Random TraversalSource Selection in GremlinScriptEngine
* TINKERPOP-1795 Getting Lambda comparator message for .profile() step
* TINKERPOP-1796 Driver connection pool SSL properties missing
* TINKERPOP-1797 LambdaRestrictionStrategy and LambdaMapStep in `by()`-modulation.
* TINKERPOP-1798 MutationListener.vertexPropertyChanged oldValue should be a VertexProperty
* TINKERPOP-1801 OLAP profile() step return incorrect timing
* TINKERPOP-1802 hasId() fails for empty collections
* TINKERPOP-1803 inject() doesn't re-attach with remote traversals
* TINKERPOP-1819 documentation query and description mismatch
* TINKERPOP-1821 Consistent behavior of self-referencing edges
* TINKERPOP-1825 Gremlin .NET: Constant() step has incorrect parameter defined
* TINKERPOP-1830 Race condition in Tinkergraph index creation
* TINKERPOP-1832 TraversalHelper.replaceStep sets previousStep to the wrong step
* TINKERPOP-1846 LambdaRestrictionStrategy not triggering for Lambda scripts
* TINKERPOP-1848 Fix g:Date assertion in python tests
* TINKERPOP-1851 Gremlin long options for -e and -i are not working properly

==== Improvements

* TINKERPOP-1661 Docker-built documentation does not always point locally
* TINKERPOP-1725 DotNet GLV: Make traversal generation deterministic
* TINKERPOP-1734 DSL for Gremlin .NET
* TINKERPOP-1746 Better error message on wrong ordering of emit()/until()/has()
* TINKERPOP-1752 Gremlin.Net: Generate completely type-safe methods
* TINKERPOP-1756 Provide a way to easily mock a RemoteConnection for tests
* TINKERPOP-1759 Improve hashcode and equals for Traverser implementations
* TINKERPOP-1768 Bump to Jackson 2.8.10
* TINKERPOP-1770 Remote traversal timeout
* TINKERPOP-1771 gremlin.bat doesn't support paths containing spaces
* TINKERPOP-1779 Bump to GMavenPlus 1.6
* TINKERPOP-1784 Gremlin Language Test Suite
* TINKERPOP-1785 Gremlin.Net should be strong-name signed
* TINKERPOP-1786 Recipe and missing manifest items for Spark on Yarn
* TINKERPOP-1787 Allow :remote command to accept a user defined Cluster instance
* TINKERPOP-1806 Consistently use Gremlin.Net instead of Gremlin-DotNet
* TINKERPOP-1807 Gremlin-Python doesn't support GraphSON types g:Date, g:Timestamp and g:UUID
* TINKERPOP-1808 Add ability to get the consumer in LambdaSideEffectStep
* TINKERPOP-1811 Improve error reporting for serialization errors between gremlin-python and gremlin-server
* TINKERPOP-1812 ProfileTest assumes that graph implementations will not add their own steps
* TINKERPOP-1813 Subgraph step requires the graph API
* TINKERPOP-1814 Some process tests require the graph API
* TINKERPOP-1820 Include .NET GLV tests on TravisCI
* TINKERPOP-1824 Update netty version to 4.0.52
* TINKERPOP-1827 Gremlin .NET: Test Suite Runner
* TINKERPOP-1829 Improve flexibility of detachment for EventStrategy
* TINKERPOP-1833 DetachedEdge.Builder#setInV and setOutV doesn't return the builder
* TINKERPOP-1835 Bump Netty 4.0.53
* TINKERPOP-1837 Gremlin .NET: Provide type coercion between IDictionary<K, V> instances

[[release-3-2-6]]
=== TinkerPop 3.2.6 (Release Date: August 21, 2017)

This release also includes changes from <<release-3-1-8, 3.1.8>>.

* Bumped to Netty 4.0.50
* Registered `HashMap$TreeNode` to Gryo.
* Fixed a lambda-leak in `SackValueStep` where `BiFunction` must be tested for true lambda status.
* Fixed a bug in `RangeByIsCountStrategy` that broke any `ConnectiveStep` that included a child traversal with an optimizable pattern.
* Allowed access to `InjectStep.injections` for `TraversalStrategy` analysis.
* Exceptions that occur during result iteration in Gremlin Server will now return `SCRIPT_EVALUATION_EXCEPTION` rather than `SERVER_ERROR`.
* `AddEdgeStep` attaches detached vertices prior to edge creation.
* Added graph element GraphSON serializers in Gremlin-Python.
* Initialization scripts for Gremlin Server will not timeout.
* Added Gremlin.Net.
* `ProfileTest` is now less stringent about assertions which will reduce burdens on providers.
* `GremlinExecutor` begins timeout of script evaluation at the time the script was submitted and not from the time it began evaluation.
* Added Gremlin.Net.
* `ReferenceFactory` and `DetachedFactory` now detach elements in collections accordingly.
* Deprecated `GryoLiteMessageSerializerV1d0` in favor of `HaltedTraverserStrategy`.
* Deprecated the `useMapperFromGraph` configuration option for Gremlin Server serializers.
* `JavaTranslator` is now smart about handling `BulkSet` and `Tree`.
* Added annotations to the traversal metrics pretty print.
* `EdgeOtherVertexStep` is no longer final and can be extended by providers.
* `EdgeVertexStep` is no longer final and can be extended by providers.
* Deprecated `Transaction.submit(Function)`.
* Fixed `HADOOP_GREMLIN_LIBS` parsing for Windows.
* Improved GraphSON serialization performance around `VertexProperty`.
* Changed some tests in `EventStrategyProcessTest` which were enforcing some unintended semantics around transaction state.
* Added WsAndHttpChannelizer and SaslAndHttpBasicAuthenticationHandler to be allow for servicing Http and Websocket requests to the same server
* Added deep copy of `Bytecode` to `DefaultTraversal.clone()`.

==== Bugs

* TINKERPOP-1385 Refactor Profiling test cases
* TINKERPOP-1679 Detached side-effects aren't attached when remoted
* TINKERPOP-1683 AbstractHadoopGraphComputer on Windows
* TINKERPOP-1691 Some EventStrategyProcessTest assume element state is synced in memory
* TINKERPOP-1704 XXXTranslators are not being respective of BulkSet and Tree.
* TINKERPOP-1727 Bytecode object shallow copied when traversals are cloned
* TINKERPOP-1742 RangeByIsCountStrategy fails for ConnectiveSteps
* TINKERPOP-1743 LambdaRestrictionStrategy does not catch lambdas passed to sack()
* TINKERPOP-1744 Gremlin .NET: Exception from sync execution gets wrapped in AggregateException

==== Improvements

* TINKERPOP-741 Remove Options For Transaction Retry
* TINKERPOP-915 Gremlin Server supports REST and Websockets simultanteously
* TINKERPOP-920 Test case needed for ensuring same cardinality for key.
* TINKERPOP-1552 C# Gremlin Language Variant
* TINKERPOP-1669 EdgeVertexStep should be designed for extension
* TINKERPOP-1676 Improve GraphSON 2.0 Performance  *(breaking)*
* TINKERPOP-1688 Include TraversalMetrics annotation in pretty print
* TINKERPOP-1694 Deprecate useMapperFromGraph
* TINKERPOP-1701 HaltedTraverserStrategy should recurse into collections for detachment.
* TINKERPOP-1703 Make EdgeOtherVertexStep non-final
* TINKERPOP-1708 Add a "Note on Scopes" document
* TINKERPOP-1709 Add a list of all the steps that support by()/from()/to()/as()/option()
* TINKERPOP-1710 Add a note on tree() by-modulation and uniqueness of tree branches.
* TINKERPOP-1714 Gremlin Server scriptEvaluationTimeout should take into account request arrival time
* TINKERPOP-1718 Deprecate GryoLiteMessageSerializerV1d0
* TINKERPOP-1748 Callout comments break code snippets
* TINKERPOP-1749 Bump to Netty 4.0.50

[[release-3-2-5]]
=== TinkerPop 3.2.5 (Release Date: June 12, 2017)

This release also includes changes from <<release-3-1-7, 3.1.7>>.

* Fixed folding of multiple `hasId()` steps into `GraphStep`.
* Added string performance options to `StarGraph`.
* Fixed a bug in `until(predicate)` where it was actually calling `emit(predicate)`.
* Fixed inconsistency in GraphSON serialization of `Path` where properties of graph elements were being included when serialized.
* Improved performance and memory usage of GraphSON when serializing `TinkerGraph` and graph elements.
* Removed use of `stream()` in `DetachedEdge` and `DetachedVertex`.
* Deprecated a constructor in `DetachedEdge` that made use of `Pair` in favor of a new one that just uses the objects that were in the `Pair`.
* Improved error messaging on the `g.addV(Object...)` when passing an invalid arguments.
* Reduced memory usage for TinkerGraph deserialization in GraphSON by streaming vertices and edges.
* Added the `gremlin-archetype-dsl` to demonstrate how to structure a Maven project for a DSL.
* Developed and documented patterns for Domain Specific Language implementations.
* Removed the Groovy dependency from `gremlin-python` and used Groovy Templates and the `gmavenplus-plugin` to generate the python GLV classes.
* Now using Groovy `[...]` map notation in `GroovyTranslator` instead of `new LinkedHashMap(){{ }}`.
* Maintained type information on `Traversal.promise()`.
* Propagated exception to `Future` instead of calling thread in `RemoteConnection`.
* Fixed a bug in `RepeatUnrollStrategy` where `LoopsStep` and `LambdaHolder` should invalidate the strategy's application.
* Deprecated `authentication.className` setting in favor of using `authentication.authenticator`.
* Added `authentication.authenticationHandler` setting.
* Added abstraction to authentication to allow users to plug in their own `AbstractAuthenticationHandler` implementations.
* Fixed a `NullPointerException` bug in `B_LP_O_S_SE_SL_Traverser`.
* `PathRetractionStrategy` now uses the marker-model to reduce recursive lookups of invalidating steps.
* `ProfileStrategy` now uses the marker-model to reduce recursive lookups of `ProfileSideEffectStep`.
* `Mutating` steps now implement `Scoping` interface.
* Fixed a step id compilation bug in `AddVertexStartStep`, `AddVertexStep`, `AddEdgeStep`, and `AddPropertyStep`.
* Added more details to Gremlin Server client side messages - exception hierarchy and stack trace.
* Deprecated "Exception-Class" in the Gremlin Server HTTP protocol in favor of the new "exceptions" field.
* De-registered metrics on Gremlin Server shutdown.
* Added "help" command option on `:remote config` for plugins that support that feature in the Gremlin Console.
* Allowed for multiple scripts and related arguments to be passed to `gremlin.sh` via `-i` and `-e`.
* `LABELED_PATH` requirement is now set if any step in the traversal is labeled.
* Updated `PathRetractionStrategy` to not run if the provided traversal contains a `VertexProgramStep` that has a `LABELED_PATH` requirement.
* Added various metrics to the `GremlinGroovyScriptEngine` around script compilation and exposed them in Gremlin Server.
* Moved the `caffeine` dependency down to `gremlin-groovy` and out of `gremlin-server`.
* Improved script compilation in `GremlinGroovyScriptEngine` to use better caching, log long compile times and prevent failed compilations from recompiling on future requests.
* Synchronized script compilation.
* Logged Script compilation times.
* Prevented failed scripts from recompiling.
* Logged warnings for scripts that take "too long" to compile.
* Improved memory usage of the `GremlinGroovyScriptEngine`.
* Added `cyclicPath().from().to().by()` support to `GraphTraversal`.
* Added `simplePath().from().to().by()` support to `GraphTraversal`.
* Added `path().from().to()` support to `GraphTraversal` so sub-paths can be isolated from the current path.
* Added `FromToModulating` interface for use with `to()`- and `from()`-based step modulators.
* Added `Path.subPath()` which supports isolating a sub-path from `Path` via to/from-labels.
* Fixed `NullPointerException` in `GraphMLReader` that occurred when an `<edge>` didn't have an ID field and the base graph supported ID assignment.
* Added `ScopingStrategy` which will computer and provide all `Scoping` steps with the path labels of the global `Traversal`.
* Split `ComputerVerificationStrategy` into two strategies: `ComputerVerificationStrategy` and `ComputerFinalizationStrategy`.
* Removed `HasTest.g_V_hasId_compilationEquality` from process test suite as it makes too many assumptions about provider compilation.
* Deprecated `CustomizerProvider` infrastructure.
* Deprecated `PluginAcceptor` infrastructure.
* Improved consistency of the application of bindings to `GremlinScriptEngine` implementations in the `BindingsGremlinPlugin`.
* Fixed a bug in OLAP `ComputerAwareStep` where end-step labels were not being appended to the traverser correctly.
* Refactor `SparkContext` handler to support external kill and stop operations.
* Fixed an optimization bug in `LazyBarrierStrategy` around appending barriers to the end of a `Traversal`.
* Fixed an optimization bug in `PathRetractionStrategy` around appending barriers to the end of a `Traversal`.
* `TraverserIterator` in GremlinServer is smart to try and bulk traversers prior to network I/O.
* Improved error handling of compilation failures for very large or highly parameterized script sent to Gremlin Server.
* Fixed a bug in `RangeByIsCountStrategy` that changed the meaning of inner traversals.
* Improved Gremlin-Python Driver implementation by adding a threaded client with basic connection pooling and support for pluggable websocket clients.
* Changed `GraphManager` from a final class implementation to an interface.
* Updated `GraphManager` interface to include methods for opening/instantiating a graph and closing a graph.
* Implemented `DefaultGraphManager` to include previous `GraphManager` functionality and adhere to updated interface.
* Deprecated `GraphManager.getGraphs()` and added `GraphManager.getGraphNames()`.
* Deprecated `GraphManager.getTraversalSources()` and added `GraphManager.getTraversalSourceNames()`.
* Fixed a bug so now users can supply a YAML with an empty `staticVariableTypes` to be used by the `FileSandboxExtension`

==== Bugs

* TINKERPOP-1258 HasTest.g_V_hasId_compilationEquality makes GraphStep assumptions
* TINKERPOP-1528 CountByIsRangeStrategy fails for a particular query
* TINKERPOP-1626 choose() is buggy in OLAP
* TINKERPOP-1638 count() is optimized away in where()
* TINKERPOP-1640 ComputerVerificationStrategy gives false errors
* TINKERPOP-1652 Disable PathRetractionStrategy strategy if VertexProgramStep has LABELLED_PATH requirement
* TINKERPOP-1660 Documentation links should not link to TINKERPOP-xxxx branches
* TINKERPOP-1666 NPE in FileSandboxExtension if staticVariableTypes is empty in supplied YAML file
* TINKERPOP-1668 RepeatUnrollStrategy should not execute if there is a LoopStep used.
* TINKERPOP-1670 End type lost when using promise()
* TINKERPOP-1673 GroovyTranslator produces Gremlin that can't execute on :remote
* TINKERPOP-1675 RemoteStep#processNextStart() throws CompletionException instead of underlying exception
* TINKERPOP-1681 Multiple hasId's are or'd into GraphStep

==== Improvements

* TINKERPOP-761 Some basic mathematical functions / steps
* TINKERPOP-786 Patterns for DSL Development
* TINKERPOP-1044 ResponseMessage should contain server-side exception name.
* TINKERPOP-1095 Create a custom ScriptContext
* TINKERPOP-1266 Make memory available to benchmarks configurable
* TINKERPOP-1303 add help for :remote config for Gephi Plugin
* TINKERPOP-1340 docs do not state at what version an API was introduced (or deprecated)
* TINKERPOP-1387 from and to modulators for path steps
* TINKERPOP-1438 Consider GraphManager as an interface*(breaking)*
* TINKERPOP-1453 Allow Gremlin-Python to handle asynchronous failure
* TINKERPOP-1577 Provide support for Python3 or Python2 in the Docker builds.
* TINKERPOP-1599 implement real gremlin-python driver
* TINKERPOP-1614 Improve documentation for Graph.V() and Graph.E() on main docs page
* TINKERPOP-1618 Remove groovy dependency from gremlin-python
* TINKERPOP-1627 LazyBarrierStrategy should not append an end barrier.
* TINKERPOP-1631 Fix visibility issues with the BindingsGremlinPlugin
* TINKERPOP-1634 Deprecate old methods of GremlinGroovyScriptEngine customization
* TINKERPOP-1642 Improve performance of mutating traversals
* TINKERPOP-1644 Improve script compilation process and include metrics
* TINKERPOP-1653 Allow multiple scripts with arguments to be passed to the Console
* TINKERPOP-1657 Provide abstraction to easily allow different HttpAuth schemes
* TINKERPOP-1663 Validate a maximum for the number of parameters passed to Gremlin Server
* TINKERPOP-1665 Remove unittest from Gremlin-Python tests
* TINKERPOP-1671 Default method for RemoteConnection.submitAsync throws exception from submit on calling thread instead of failing the future
* TINKERPOP-1677 Bump Groovy to 2.4.11
* TINKERPOP-1680 Add string performance options to StarGraph

[[release-3-2-4]]
=== TinkerPop 3.2.4 (Release Date: February 8, 2017)

This release also includes changes from <<release-3-1-6, 3.1.6>>.

* Fixed a bug where `PathProcessor.keepLabels` were not being pushed down into child traversals by `PathRetractionStrategy`.
* Added default `MessagePassingReductionStrategy` for `GraphComputer` that can reduce the number of message passing iterations.
* Fixed a bug associated with user-provided maps and `GroupSideEffectStep`.
* `GroupBiOperator` no longer maintains a detached traversal and thus, no more side-effect related OLAP inconsistencies.
* Added `ProjectedTraverser` which wraps a traverser with a `List<Object>` of projected data.
* Fixed an optimization bug in `CollectingBarrierSteps` where the barrier was being consumed on each `addBarrier()`.
* `OrderGlobalStep` and `SampleGlobalStep` use `ProjectedTraverser` and now can work up to the local star graph in OLAP.
* SASL negotiation supports both a byte array and Base64 encoded bytes as a string for authentication to Gremlin Server.
* Deprecated all test suites in `gremlin-groovy-test` - Graph Providers no longer need to implement these.
* Deprecated `TinkerIoRegistry` replacing it with the more consistently named `TinkerIoRegistryV1d0`.
* Made error messaging more consistent during result iteration timeouts in Gremlin Server.
* Fixed a memory leak in the classloader for the `GremlinGroovyScriptEngine` where classes in the loader were not releasing from memory as a strong reference was always maintained.
* `PathRetractionStrategy` does not add a `NoOpBarrierStep` to the end of local children as its wasted computation in 99% of traversals.
* Fixed a bug in `AddVertexStartStep` where if a side-effect was being used in the parametrization, an NPE occurred.
* Fixed a bug in `LazyBarrierStrategy` where `profile()` was deactivating it accidentally.
* Fixed a bug in `RepeatUnrollStrategy` where stateful `DedupGlobalStep` was cloned and thus, maintained two deduplication sets.
* Added documentation around "terminal steps" in Gremlin: `hasNext()`, `next()`, `toList()`, etc.
* Added specific GraphSON serializers for `RequestMessage` and `ResponseMessage` in GraphSON 2.0.
* Added `CloseableIterator` to allow `Graph` providers who open expensive resources a way to let users release them.
* Fixed minor bug in `gremlin-driver` where closing a session-based `Client` without initializing it could generate an error.
* Relieved synchronization pressure in various areas of `TinkerGraphComputer`.
* Fixed an optimization bug in OLAP-based `DedupGlobalStep` where deduping occurred twice.
* `MemoryComputeKey` now implements `Cloneable` which is useful for `BiOperator` reducers that maintain thread-unsafe state.
* `TinkerGraphComputer` now supports distributed `Memory` with lock-free partition aggregation.
* `TinkerGraph` Gryo and GraphSON deserialization is now configured to use multi-properties.
* Changed behavior of `ElementHelper.areEqual(Property, Property)` to not throw exceptions with `null` arguments.
* Added `GryoVersion` for future flexibility when introducing a new verison of Gryo and moved serializer registrations to it.
* Fixed Gryo serialization of `ConnectiveP` instances.
* Lessened the severity of Gremlin Server logging when it encounters two or more serializers addressing the same mime type.
* Bumped to Netty 4.0.42.final.
* Added `ByteBuffer`, `InetAddress`, `Timestamp` to the list of Gryo supported classes.
* Fixed Gryo serialization of `Class`.
* Fixed GraphSON serialization of enums like `T`, `P`, etc. where values were overriding each other in the GraphSON type registry.
* Fixed a bug in Gremlin-Python around `__.__()` and `__.start()`.
* Fixed a bug around long serialization in Gremlin-Python when using Python3.
* Deprecated `TraversalSource.withBindings()` as it is no longer needed in Gremlin-Java and never was needed for other variants.
* Fixed a bug in Gremlin-Java `Bytecode` where anonymous traversals were not aware of parent bindings.
* Fixed a bug in Gremlin-Java GraphSON deserialization around `P.within()` and `P.without()`.
* Converted Spark process suite tests to "integration" tests.
* Fixed a bug in `InlineFilterStrategy` having to do with folding `HasContainers` into `VertexStep`.
* Deprecated `HasContainer.makeHasContainers()` which was used to dissect `AndP` and shouldn't be used at the TinkerPop-level.
* `GraphTraversal.has()` now will try and fold-left `HasContainer` if end step is a `HasContainerHolder`.
* Created explicit `P`-predicate methods for `GraphTraversal.hasXXX()`.
* Fixed a bug in `FilterRankStrategy` around `where().by()` ordering.
* Added another optimization in `RangeByIsCountStrategy`, that removes `count().is()` altogether if it's not needed.
* Fixed a OLAP `MatchStep.clone()`-bug that occurs when the `match()` is in a local child.
* Added another optimization in `RangeByIsCountStrategy`, that removes `count().is()` altogether if it's not needed.
* Fixed a bug in `RangeByIsCountStrategy` where labeled parents shouldn't have the strategy applied to their children.
* Fixed a bug in `PathRetractionStrategy` where `MatchEndStep` labels were being dropped when they shouldn't be.
* Added `TinkerGraphCountStrategy` which translates `g.V().map*.count()` patterns into direct `Map.size()` calls in `TinkerGraph`.
* Added `Path.head()` and `Path.isEmpty()` with default method implementations.
* Fixed a `NoSuchElementException` bug with `GroupXXXStep` where if the reduced `TraverserSet` is empty, don't add the key/value.
* Fixed a `NullPointerException` bug with profiling `GroupSideEffectStep` in OLTP.
* Improved ability to release resources in `GraphProvider` instances in the test suite.
* Factored `GremlinPlugin` functionality out of gremlin-groovy and into gremlin-core - related classes were deprecated.
* Added a `force` option for killing sessions without waiting for transaction close or timeout of a currently running job or multiple jobs.
* Deprecated `Session.kill()` and `Session.manualKill()`.
* Added `Traversal.promise()` method to allow for asynchronous traversal processing on "remote" traversals.
* Deprecated `RemoteConnection.submit(Bytecode)` in favor of `submitAsync(Bytecode)`.
* Added `choose(predicate,traversal)` and `choose(traversal,traversal)` to effect if/then-semantics (no else). Equivalent to `choose(x,y,identity())`.
* Removed `ImmutablePath.TailPath` as it is no longer required with new recursion model.
* Removed call stack recursion in `ImmutablePath`.
* Gremlin-Python serializes `Bytecode` as an object (instead of a JSON string) when submit over the `RemoteConnection`.
* Fixed the handling of the `DriverRemoteConnection` pass-through configurations to the driver.
* `IncidentToAdjacentStrategy` now uses a hidden label marker model to avoid repeated recursion for invalidating steps.
* `PathProcessorStrategy` can inline certain `where(traversal)`-steps in order to increase the likelihood of star-local children.
* `SparkGraphComputer` no longer starts a worker iteration if the worker's partition is empty.
* Added `ProjectStep.getProjectKeys()` for strategies that rely on such information.
* Added `VertexFeatures.supportsDuplicateMultiProperties()` for graphs that only support unique values in multi-properties.
* Deprecated the "performance" tests in `OptIn`.
* Deprecated `getInstance()` methods in favor of `instance()` for better consistency with the rest of the API.
* Block calls to "remote" traversal side-effects until the traversal read is complete which signifies an end to iteration.
* Added `Pick.none` and `Pick.any` to the serializers and importers.
* Added a class loader to `TraversalStrategies.GlobalCache` which guarantees strategies are registered prior to `GlobalCache.getStrategies()`.
* Fixed a severe bug where `GraphComputer` strategies are not being loaded until the second use of the traversal source.
* The root traversal now throws regular `NoSuchElementException` instead of `FastNoSuchElementException`. (*breaking*)
* Added a short sleep to prevent traversal from finishing before it can be interrupted during `TraversalInterruptionComputerTest`.
* Added support for SSL client authentication

==== Bugs

* TINKERPOP-1380 dedup() doesn't dedup in rare cases
* TINKERPOP-1384 Description of filter function in traversal documentation
* TINKERPOP-1428 profile() throws NPE for union(group, group)
* TINKERPOP-1521 Mutating steps don't recognize side-effects
* TINKERPOP-1525 Plug VertexProgram iteration leak on empty Spark RDD partitions
* TINKERPOP-1534 Gremlin Server instances leaking in tests
* TINKERPOP-1537 Python tests should not use hard-coded number of workers
* TINKERPOP-1547 Two bugs found associated with MatchStep: Path retraction and range count.
* TINKERPOP-1548 Traversals can complete before interrupted in TraversalInterruptionComputerTest
* TINKERPOP-1560 Cache in GroovyClassLoader may continue to grow
* TINKERPOP-1561 gremiln-python GraphSONWriter doesn't properly serialize long in Python 3.5
* TINKERPOP-1567 GraphSON deserialization fails with within('a')
* TINKERPOP-1573 Bindings don't work in coalesce
* TINKERPOP-1576 gremlin-python calls non-existent methods
* TINKERPOP-1581 Gremlin-Python driver connection is not thread safe.
* TINKERPOP-1583 PathRetractionStrategy retracts keys that are actually needed
* TINKERPOP-1585 OLAP dedup over non elements
* TINKERPOP-1587 Gremlin Server Subgraph Cardinality Not Respected
* TINKERPOP-1594 LazyBarrierStrategy does not activate with ProfileStep
* TINKERPOP-1605 gremlin-console 3.2.3 -e can no longer take paths relative to current working directory

==== Improvements

* TINKERPOP-887 FastNoSuchElementException hides stack trace in client code
* TINKERPOP-919 Features needs to specify whether 2 vertex properties with same key/value is allowed.
* TINKERPOP-932 Add ability to cancel script execution associated with a Gremlin Server Session
* TINKERPOP-1248 OrderGlobalStep should use local star graph to compute sorts, prior to reduction.
* TINKERPOP-1261 Side-effect group().by() can't handle user-defined maps
* TINKERPOP-1292 TinkerGraphComputer VertexProgramInterceptors
* TINKERPOP-1372 ImmutablePath should not use Java recursion (call stacks are wack)
* TINKERPOP-1433 Add steps to dev docs to help committers get their keys in order
* TINKERPOP-1434 Block calls to traversal side-effects until read is complete
* TINKERPOP-1471 IncidentToAdjacentStrategy use hidden marker to avoid repeated recursion.
* TINKERPOP-1473 Given PathRetractionStrategy, PathProcessorStrategy can be extended to support partial where() inlining.
* TINKERPOP-1482 has(x).has(y) chains should be has(x.and(y))
* TINKERPOP-1490 Provider a Future based Traversal.async(Function<Traversal,V>) terminal step
* TINKERPOP-1502 Chained has()-steps should simply left-append HasContainers in Gremlin-Java.
* TINKERPOP-1507 Pick.any and Pick.none are not in GraphSON or Gremlin-Python
* TINKERPOP-1508 Add choose(predicate,trueTraversal)
* TINKERPOP-1527 Do not override registered strategies in TraversalStrategies.GlobalCache
* TINKERPOP-1530 Consistent use of instance()
* TINKERPOP-1539 Create a ComplexTraversalTest with crazy nested gnarly traversals.
* TINKERPOP-1542 Add Path.isEmpty() with a default implementation.
* TINKERPOP-1562 Migrate ScriptEngine-related code to gremlin-core
* TINKERPOP-1570 Bump to Netty 4.0.42
* TINKERPOP-1582 TraversalOpProcessor does not support custom serializers
* TINKERPOP-1584 Add gryo serializers to support types covered in GraphSON
* TINKERPOP-1588 Added Terminal Steps section to the docs
* TINKERPOP-1589 Re-Introduce CloseableIterator
* TINKERPOP-1590 Create TinkerWorkerMemory and Partitioned Vertices
* TINKERPOP-1600 Consistent use of base 64 encoded bytes for SASL negotiation
* TINKERPOP-1602 Support SSL client certificate authentication
* TINKERPOP-1606 Refactor GroupStep to not have the reduction traversal included in its BiOperator.
* TINKERPOP-1610 Deprecate gremlin-groovy-test provider based tests
* TINKERPOP-1617 Create a SingleIterationStrategy which will do its best to rewrite OLAP traversals to not message pass.

[[release-3-2-3]]
=== TinkerPop 3.2.3 (Release Date: October 17, 2016)

This release also includes changes from <<release-3-1-5, 3.1.5>>.

* Restructured Gremlin-Python's GraphSON I/O package to make it easier for users to register serializers/deserializers. (*breaking*)
* Fixed a bug with `TraversalOpProcessor` that was returning a final result prior to committing the transaction.
* Fixed a bug in `ConnectiveStrategy` where infix and/or was not correctly reasoning on `choose()` `HasNextStep` injections.
* Increased performance of `CredentialGraph` authentication.
* Removed Java 8 stream usage from `TraversalHelper` for performance reasons.
* Fixed a bug in `RepeatStep` where `emit().as('x')` wasn't adding the step labels to the emit-traverser.
* Added `GraphComputing.atMaster(boolean)` to allow steps to know whether they are executing at master or distributed at workers.
* Fixed a bug in OLAP where `DedupGlobalStep` wasn't de-duping local master traversers.
* Added `HasContainerHolder.removeHasContainer()`-method with default `UnsupportedOperationException` implementation.
* `TraversalSource.withComputer()` is simplified to add a `VertexProgramStrategy`. Easier for language variants.
* Fixed a `Set`, `List`, `Map` bug in the various `Translators` where such collections were not being internally translated.
* Fixed a `Bytecode` bug where nested structures (map, list, set) were not being analyzed for bindings and bytecode conversions.
* Fixed a `String` bug in `GroovyTranslator` and `PythonTranslator` where if the string has double-quotes it now uses """ """.
* Added a default `TraversalStrategy.getConfiguration()` which returns the configuration needed to construct the strategy.
* `Computer` instances can be created with `Computer.create(Configuration)` and accessed via `Computer.getConf()`.
* Every `TraversalStrategy` can be created via a `Configuration` and a static `MyStrategy.create(Configuration)`.
* Added language-agnostic `TraversalStrategy` support in `Bytecode`.
* Added `PartitionStrategy.Builder.readPartitions()` and deprecated `PartitionStrategy.Builder.addPartition()`.
* A new version of `LazyBarrierStrategy` has been created and added to the default strategies.
* `FilterRankStrategy` now propagates labels "right" over non-`Scoping` filters.
* Fixed a bug in `ConnectiveP` where nested equivalent connectives should be inlined.
* Fixed a bug in `IncidentToAdjacentStrategy` where `TreeStep` traversals were allowed.
* Fixed a end-step label bug in `MatchPredicateStrategy`.
* Fixed a bug in `MatchPredicateStrategy` where inlined traversals did not have strategies applied to it.
* Fixed a bug in `RepeatUnrollStrategy` where inlined traversal did not have strategies applied to it.
* Fixed padding of prompt in Gremlin Console when the number of lines went beyond a single digit.
* Fixed GraphSON 2.0 namespace for `TinkerGraph` to be "tinker" instead of "gremlin".
* Dropped serialization support in GraphSON 2.0 for `Calendar`, `TimeZone`, and `Timestamp`.
* Added `TraversalHelper.copyLabels()` for copying (or moving) labels form one step to another.
* Added `TraversalHelper.applySingleLevelStrategies()` which will apply a subset of strategies but not walk the child tree.
* Added the concept that hidden labels using during traversal compilation are removed at the end during `StandardVerificationStrategy`. (*breaking*)
* Added `InlineFilterStrategy` which will determine if various `TraversalParent` children are filters and if so, inline them.
* Removed `IdentityRemovalStrategy` from the default listing as its not worth the clock cycles.
* Removed the "!" symbol in `NotStep.toString()` as it is confusing and the `NotStep`-name is sufficient.
* Fixed a bug in `TraversalVertexProgram` (OLAP) around ordering and connectives (i.e. `and()` and `or()`).
* Added `AbstractGremlinProcessTest.checkOrderedResults()` to make testing ordered results easier.
* `AbstractLambdaTraversal` now supports a `bypassTraversal` where it is possible for strategies to redefine such lambda traversals.
* Added an internal utility `ClassFilterStep` which determines if the traverser object's class is an instance of the provided class.
* `ConnectiveStep` extends `FilterStep` and thus, is more appropriately categorized in the step hierarchy.
* `PropertyMapStep` supports a provided traversal for accessing the properties of the element. (*breaking*)
* `SubgraphStrategy` now supports vertex property filtering.
* Fixed a bug in Gremlin-Python `P` where predicates reversed the order of the predicates.
* Added tests to `DedupTest` for the `dedup(Scope, String...)` overload.
* Added more detailed reference documentation for IO formats.
* Fixed a bug in serialization of `Lambda` instances in GraphSON, which prevented their use in remote traversals.
* Fixed a naming bug in Gremlin-Python where `P._and` and `P._or` should be `P.and_` and `P.or_`. (*breaking*)
* `where()` predicate-based steps now support `by()`-modulation.
* Added Gryo serialization for `Bytecode`.
* Moved utility-based serializers to `UtilSerializers` for Gryo - these classes were private and hence this change is non-breaking.
* `TraversalRing` returns a `null` if it does not contain traversals (previously `IdentityTraversal`).
* Deprecated `Graph.Exceptions.elementNotFoundException()` as it was not used in the code base outside of the test suite.
* Fixed a `JavaTranslator` bug where `Bytecode` instructions were being mutated during translation.
* Added `Path` to Gremlin-Python with respective GraphSON 2.0 deserializer.
* `Traversal` and `TraversalSource` now implement `AutoCloseable`.
* Added "keep-alive" functionality to the Java driver, which will send a heartbeat to the server when normal request activity on a connection stops for a period of time.
* Renamed the `empty.result.indicator` preference to `result.indicator.null` in Gremlin Console
* If `result.indicator.null` is set to an empty string, then no "result line" is printed in Gremlin Console.
* Deprecated `reconnectInitialDelay` on the Java driver.
* Added some validations to `Cluster` instance building.
* Produced better errors in `readGraph` of `GryoReader` and `GraphSONReader` if a `Vertex` cannot be found in the cache on edge loading.
* VertexPrograms can now declare traverser requirements, e.g. to have access to the path when used with `.program()`.
* New build options for `gremlin-python` where `-DglvPython` is no longer required.
* Added missing `InetAddress` to GraphSON extension module.
* Added new recipe for "Pagination".
* Added new recipe for "Recommendation".
* Added functionality to Gremlin-Server REST endpoint to forward Exception Messages and Class in HTTP Response
* Gremlin Server `TraversalOpProcessor` now returns confirmation upon `Op` `close`.
* Added `close` method Java driver and Python driver `DriverRemoteTraversalSideEffects`.

==== Bugs

* TINKERPOP-1423 IncidentToAdjacentStrategy should be disabled for tree steps
* TINKERPOP-1440 g:Path needs a GraphSON deserializer in Gremlin-Python
* TINKERPOP-1457 Groovy Lambdas for remote traversals not serializable
* TINKERPOP-1458 Gremlin Server doesn't return confirmation upon Traversal OpProcessor "close" op
* TINKERPOP-1466 PeerPressureTest has been failing recently
* TINKERPOP-1472 RepeatUnrollStrategy does not semi-compile inlined repeat traversal
* TINKERPOP-1476 TinkerGraph does not get typed with the right type name in GraphSON
* TINKERPOP-1495 Global list deduplication doesn't work in OLAP
* TINKERPOP-1500 and/or infix and choose() do not work correctly.
* TINKERPOP-1511 Remote client addV, V()

==== Improvements

* TINKERPOP-790 Implement AutoCloseable on TraversalSource
* TINKERPOP-944 Deprecate Graph.Exceptions.elementNotFound
* TINKERPOP-1189 SimpleAuthenticator over HttpChannelizer makes Gremlin Server pretty slow and consumes more CPU
* TINKERPOP-1249 Gremlin driver to periodically issue ping / heartbeat to gremlin server
* TINKERPOP-1280 VertexPrograms should declare traverser requirements
* TINKERPOP-1330 by()-modulation for where()
* TINKERPOP-1409 Make the "null" return in the gremlin console into something more understandable  *(breaking)*
* TINKERPOP-1431 Documentation generation requires tests to execute on gremlin-python
* TINKERPOP-1437 Add tests for dedup(Scope) in DedupTest
* TINKERPOP-1444 Benchmark bytecode->Traversal creation and implement GremlinServer cache if necessary.
* TINKERPOP-1448 gremlin-python should be Python 2/3 compatible
* TINKERPOP-1449 Streamline gremlin-python build
* TINKERPOP-1455 Provide String-based withStrategy()/withoutStrategy() for language variant usage
* TINKERPOP-1456 Support SubgraphStrategy.vertexProperties().
* TINKERPOP-1460 Deprecate reconnectInitialDelay in Java driver
* TINKERPOP-1464 Gryo Serialization for Bytecode
* TINKERPOP-1469 Get rid of Stream-usage in TraversalHelper
* TINKERPOP-1470 InlineFilterStrategy should try and P.or() has() children in OrSteps.
* TINKERPOP-1486 Improve API of RemoteConnection
* TINKERPOP-1487 Reference Documentation for IO
* TINKERPOP-1488 Make LazyBarrierStrategy part of the default TraversalStrategies *(breaking)*
* TINKERPOP-1492 RemoteStrategy or the RemoteConnection should append a lazy barrier().
* TINKERPOP-1423 IncidentToAdjacentStrategy should be disabled for tree steps
* TINKERPOP-1440 g:Path needs a GraphSON deserializer in Gremlin-Python
* TINKERPOP-1457 Groovy Lambdas for remote traversals not serializable
* TINKERPOP-1458 Gremlin Server doesn't return confirmation upon Traversal OpProcessor "close" op
* TINKERPOP-1466 PeerPressureTest has been failing recently
* TINKERPOP-1472 RepeatUnrollStrategy does not semi-compile inlined repeat traversal
* TINKERPOP-1495 Global list deduplication doesn't work in OLAP
* TINKERPOP-1500 and/or infix and choose() do not work correctly.
* TINKERPOP-1511 Remote client addV, V()

[[release-3-2-2]]
=== TinkerPop 3.2.2 (Release Date: September 6, 2016)

This release also includes changes from <<release-3-1-4, 3.1.4>>.

* Included GraphSON as a default serializer (in addition to Gryo, which was already present) in Gremlin Server if none are defined.
* Added `gremlin-python` package as a Gremlin language variant in Python.
* Added `Bytecode` which specifies the instructions and arguments used to construct a traversal.
* Created an experimental GraphSON representation of `Bytecode` that will be considered unstable until 3.3.0.
* Added `Translator` which allows from the translation of `Bytecode` into some other form (e.g. script, `Traversal`, etc.).
* Added `JavaTranslator`, `GroovyTranslator`, `PythonTranslator`, and `JythonTranslator` for translating `Bytecode` accordingly.
* Added `TranslationStrategy` to `gremlin-test` so translators can be tested against the process test suite.
* Added `Traversal.Admin.nextTraverser()` to get the next result in bulk-form (w/ default implementation).
* Added `TraversalSource.getAnonymousTraversalClass()` (w/ default implementation).
* Added `GremlinScriptEngine` interface which specifies a `eval(Bytecode, Bindings)` method.
* Deprecated `RemoteGraph` in favor of `TraversalSource.withRemote()` as it is more technically correct to tie a remote traversal to the `TraversalSource` than a `Graph` instance.
* `GremlinGroovyScriptEngine` implements `GremlinScriptEngine`.
* Added `GremlinJythonScriptEngine` which implements `GremlinScriptEngine`.
* Removed support for submitting a Java serialized `Traversal` to Gremlin Server.
* Removed a largely internal feature that supported automatic unrolling of traversers in the Gremlin Driver.
* Made it possible to directly initialize `OpProcessor` implementations with server `Settings`.
* Included GraphSON as a default serializer (in addition to Gryo, which was already present) in Gremlin Server if none are defined
* Introduced GraphSON 2.0.
* Deprecated `embedTypes` on the builder for `GraphSONMapper`.
* Bumped to Netty 4.0.40.final.
* Defaulted the `gremlinPool` setting in Gremlin Server to be zero, which will instructs it to use `Runtime.availableProcessors()` for that settings.
* Changed scope of log4j dependencies so that they would only be used in tests and the binary distributions of Gremlin Console and Server.
* Deprecated `Io.Builder.registry()` in favor of the newly introduced `Io.Builder.onMapper()`.
* Added new recipe for "Traversal Induced Values".
* Fixed a potential leak of a `ReferenceCounted` resource in Gremlin Server.
* Added class registrations for `Map.Entry` implementations to `GryoMapper`.
* Added methods to retrieve `Cluster` settings in `gremlin-driver`.
* Fixed a severe bug in `SubgraphStrategy`.
* Deprecated `SubgraphStrategy.Builder.vertexCriterion()/edgeCriterion()` in favor of `vertices()/edges()`.
* Fixed a small bug in `StandardVerificationStrategy` that caused verification to fail when `withPath` was used in conjunction with `ProfileStep`.
* Added color preferences
* Added input, result prompt preferences
* Added multi-line indicator in Gremlin Console

==== Bugs

* TINKERPOP-810 store not visible
* TINKERPOP-1151 slf4j-log4j12 / log4j is only required for testing *(breaking)*
* TINKERPOP-1383 publish-docs.sh might publish to current too early
* TINKERPOP-1390 IdentityRemoveStrategyTest fails randomly
* TINKERPOP-1400 SubgraphStrategy introduces infinite recursion if filter has Vertex/Edge steps.
* TINKERPOP-1405 profile() doesn't like withPath()

==== Improvements

* TINKERPOP-1037 Gremlin shell output coloring
* TINKERPOP-1226 Gremlin Console should :clear automagically after "Display stack trace."
* TINKERPOP-1230 Serialising lambdas for RemoteGraph
* TINKERPOP-1274 GraphSON Version 2.0
* TINKERPOP-1278 Implement Gremlin-Python and general purpose language variant test infrastructure
* TINKERPOP-1285 Gremline console does not differentiate between multi-line and single-line input
* TINKERPOP-1334 Provide a way to pull gremlin.driver.Cluster connection settings.
* TINKERPOP-1347 RemoteConnection needs to provide TraversalSideEffects. *(breaking)*
* TINKERPOP-1373 Default gremlinPool to number of cores
* TINKERPOP-1386 Bump to Netty 4.0.40.Final
* TINKERPOP-1392 Remove support for java serialized Traversal *(breaking)*
* TINKERPOP-1394 Fix links in Recipes doc
* TINKERPOP-1396 Traversal Induced Values Recipe
* TINKERPOP-1402 Impossible for graph implementations to provide a class resolver for Gryo IO
* TINKERPOP-1407 Default serializers for Gremlin Server
* TINKERPOP-1425 Use trailing underscores in gremlin-python

[[release-3-2-1]]
=== TinkerPop 3.2.1 (Release Date: July 18, 2016)

This release also includes changes from <<release-3-1-3, 3.1.3>>.

* `PathProcessor` steps now have the ability (if configured through a strategy) to drop `Traverser` path segments.
* `MatchStep` in OLTP has a lazy barrier to increase the probability of bulking.
* Added `PathRetractionStrategy` which will remove labeled path segments that will no longer be referenced.
* Added `Path.retract()` to support retracting paths based on labels.
* Optimized `ImmutablePath` and `MutablePath` equality code removing significant unnecessary object creation code.
* Bumped to Groovy 2.4.7.
* Added `RepeatUnrollStrategy` to linearize a `repeat()`-traversal if loop amount is known at compile time.
* Fixed a bug in `BranchStep` around child integration during `clone()`.
* Fixed a bug in `AbstractStep` around label set cloning.
* Added `TraversalStrategyPerformanceTest` for verifying the performance gains of optimization-based traversal strategies.
* `TraversalExplanation.prettyPrint()` exists which provides word wrapping and GremlinConsole is smart to use console width to control `toString()`.
* `TraversalOpProcessor` (`RemoteConnection`) uses `HaltedTraverserStrategy` metadata to determine detachment procedure prior to returning results.
* Allow DFS paths in `HADOOP_GREMLIN_LIBS`.
* Added a safer serializer infrastructure for use with `SparkGraphComputer` that uses `KryoSerializer` and the new `GryoRegistrator`.
* Added `HaltedTraverserStrategy` to allow users to get back different element detachments in OLAP.
* Fixed a `NullPointerException` bug around nested `group()`-steps in OLAP.
* Fixed a severe bug around halted traversers in a multi-job OLAP traversal chain.
* Ensure a separation of `GraphComputer` and `VertexProgram` configurations in `SparkGraphComputer` and `GiraphGraphComputer`.
* `PeerPressureVertexProgram` now supports dynamic initial vote strength calculations.
* Added `EmptyMemory` for ease of use when no memory exists.
* Updated `VertexComputing.generateProgram()` API to include `Memory`. *(breaking)*
* `ImmutablePath.TailPath` is now serializable like `ImmutablePath`.
* Added `ConfigurationCompilerProvider` which allows fine-grained control of some of the internal `GremlinGroovyScriptEngine` settings at the Groovy compilation level.
* Intoduced the `application/vnd.gremlin-v1.0+gryo-lite` serialization type to Gremlin Server which users "reference" elements rather than "detached".
* `GryoMapper` allows overrides of existing serializers on calls to `addCustom` on the builder.
* Added a traversal style guide to the recipes cookbook.
* Fixed a bug in master-traversal traverser propagation.
* Added useful methods for custom `VertexPrograms` to be used with `program()`-step.
* Increased the test coverage around traverser propagation within a multi-job OLAP traversal.
* Added tests to validate the status of a transaction immediately following calls to close.
* Added tests to ensure that threaded transactions cannot be re-used.
* `GraphFilter` helper methods are now more intelligent when determining edge direction/label legality.
* Added `GraphFilterStrategy` to automatically construct `GraphFilters` via traversal introspection in OLAP.
* Updated the Gephi Plugin to support Gephi 0.9.x.
* Increased the testing and scope of `TraversalHelper.isLocalStarGraph()`.
* Changed signature of `get_g_VXlistXv1_v2_v3XX_name` and `get_g_VXlistX1_2_3XX_name` of `VertexTest` to take arguments for the `Traversal` to be constructed by extending classes.
* Added `VertexProgramInterceptor` interface as a general pattern for `GraphComputer` providers to use for bypassing `GraphComputer` semantics where appropriate.
* Added `SparkStarBarrierInterceptor` that uses Spark DSL for local star graph traversals that end with a `ReducingBarrierStep`.
* Added `SparkInterceptorStrategy` which identifies which interceptor to use (if any) given the submitted `VertexProgram`.
* Added `SparkSingleIterationStrategy` that does not partition nor cache the graph RDD if the traversal does not message pass.
* Added more helper methods to `TraversalHelper` for handling scoped traversal children.
* Deprecated all "performance" tests based on "JUnit Benchmarks".
* `SparkGraphComputer` no longer shuffles empty views or empty outgoing messages in order to save time and space.
* `TraversalVertexProgram` no longer maintains empty halted traverser properties in order to save space.
* Added `List<P<V>>` constructors to `ConnectiveP`, `AndP`, and `OrP` for ease of use.
* Added support for interactive (`-i`) and execute (`-e`) modes for Gremlin Console.
* Displayed line numbers for script execution failures of `-e` and `-i`.
* Improved messaging around script execution errors in Gremlin Console.
* Added "help" support to Gremlin Console with the `-h` flag.
* Added options to better control verbosity of Gremlin Console output with `-Q`, `-V` and `-D`.
* Deprecated the `ScriptExecutor` - the `-e` option to `gremlin.sh` is now handled by `Console`.
* `Traversal` now allows cancellation with `Thread.interrupt()`.
* Added a Gremlin language variant tutorial teaching people how to embed Gremlin in a host programming language.

==== Bugs

* TINKERPOP-1281 Memory.HALTED_TRAVERSER transience is not sound.
* TINKERPOP-1305 HALTED_TRAVERSERS hold wrong information
* TINKERPOP-1307 NPE with OLTP nested group() in an OLAP group() traversal
* TINKERPOP-1323 ComputerVerificationStrategy fails for nested match() steps
* TINKERPOP-1341 UnshadedKryoAdapter fails to deserialize StarGraph when SparkConf sets spark.rdd.compress=true whereas GryoSerializer works
* TINKERPOP-1348 TraversalInterruptionTest success dependent on iteration order

==== Improvements

* TINKERPOP-818 Consider a P.type()
* TINKERPOP-946 Traversal respecting Thread.interrupt()
* TINKERPOP-947 Enforce semantics of threaded transactions as manual *(breaking)*
* TINKERPOP-1059 Add test to ensure transaction opening happens at read/write and not on close *(breaking)*
* TINKERPOP-1071 Enhance pre-processor output
* TINKERPOP-1091 Get KryoSerializer to work natively. *(breaking)*
* TINKERPOP-1120 If there is no view nor messages, don't create empty views/messages in SparkExecutor
* TINKERPOP-1144 Improve ScriptElementFactory
* TINKERPOP-1155 gremlin.sh -e doesn't log line numbers for errors
* TINKERPOP-1156 gremlin.sh could use a help text
* TINKERPOP-1157 gremlin.sh should allow you to execute a script and go interactive on error or completion
* TINKERPOP-1232 Write a tutorial demonstrating the 3 ways to write a Gremlin language variant.
* TINKERPOP-1254 Support dropping traverser path information when it is no longer needed.
* TINKERPOP-1268 Improve script execution options for console *(breaking)*
* TINKERPOP-1273 Deprecate old performance tests
* TINKERPOP-1276 Deprecate serializedResponseTimeout
* TINKERPOP-1279 Add Iterable<V> parameter constructor to ConnectiveP subclasses
* TINKERPOP-1282 Add more compliance tests around how memory and vertex compute keys are propagated in chained OLAP.
* TINKERPOP-1286 Add Recipes documentation
* TINKERPOP-1288 Support gremlin.spark.skipPartitioning configuration.
* TINKERPOP-1290 Create VertexProgramInterceptor as a pattern for GraphComputer strategies.
* TINKERPOP-1293 Implement GraphFilterStrategy as a default registration for GraphComputer
* TINKERPOP-1294 Deprecate use of junit-benchmarks
* TINKERPOP-1297 Gephi plugin on Gephi 0.9.x  *(breaking)*
* TINKERPOP-1299 Refactor TraversalVertexProgram to make it easier to understand.
* TINKERPOP-1308 Serialize to "reference" for Gremlin Server
* TINKERPOP-1310 Allow OLAP to return properties as Detached
* TINKERPOP-1321 Loosen coupling between TinkerPop serialization logic and shaded Kryo
* TINKERPOP-1322 Provide fine-grained control of CompilerConfiguration
* TINKERPOP-1328 Provide [gremlin-python] as an code executor in docs
* TINKERPOP-1331 HADOOP_GREMLIN_LIBS can only point to local file system
* TINKERPOP-1332 Improve .explain() Dialogue
* TINKERPOP-1338 Bump to Groovy 2.4.7
* TINKERPOP-1349 RepeatUnrollStrategy should unroll loops while maintaining equivalent semantics.
* TINKERPOP-1355 Design HasContainer for extension

[[release-3-2-0-incubating]]
=== TinkerPop 3.2.0 (Release Date: April 8, 2016)

This release also includes changes from <<release-3-1-2-incubating, 3.1.2-incubating>>.

* Bumped to Neo4j 2.3.3.
* Renamed variable `local` to `fs` in `HadoopGremlinPlugin` to avoid a naming conflict with `Scope.local`. *(breaking)*
* Added `GraphTraversal.optional()` which will use the inner traversal if it returns results, else it won't.
* `GroupStep` and `GroupSideEffectStep` make use of mid-traversal reducers to limit memory consumption in OLAP.
* Added `GraphTraversal.program(VertexProgram)` to allow arbitrary user vertex programs in OLAP.
* Added `GraphTraversal.project()` for creating a `Map<String,E>` given the current traverser and an arbitrary number of `by()`-modulators.
* `HADOOP_GREMLIN_LIBS` can now reference a directory in HDFS and will be used if the directory does not exist locally.
* Added `gremlin-benchmark` module with JMH benchmarking base classes that can be used for further benchmark development.
* `TraversalStrategies.GlobalCache` supports both `Graph` and `GraphComputer` strategy registrations.
* `select("a","b").by("name").by("age")`-style traversals now work in OLAP with new `PathProcessorStrategy`.
* `DedupGlobalStep` can now handle star-bound `by()`-modulators and scoped keys on `GraphComputer`.
* Added `Computer` which is a builder for `GraphComputers` that is serializable.
* `PersistedOutputRDD` now implements `PersistResultGraphAware` and thus, no more unneeded warnings when using it.
* Renamed `StandardTraversalMetrics` to `DefaultTraversalMetrics` given the `DefaultXXX`-convention throughout. *(breaking)*
* Bumped to Apache Hadoop 2.7.2.
* Fixed a bug around profiling and nested traversals.
* Added `gremlin.hadoop.defaultGraphComputer` so users can use `graph.compute()` with `HadoopGraph`.
* Added `gremlin.hadoop.graphReader` and `gremlin.hadoop.graphWriter` which can handled `XXXFormats` and `XXXRDDs`.
* Deprecated `gremlin.hadoop.graphInputFormat`, `gremlin.hadoop.graphOutputFormat`, `gremlin.spark.graphInputRDD`, and `gremlin.spark.graphOutputRDD`.
* If no configuration is provided to `HadoopPools` it uses the default configuration to create a pool once and only once per JVM.
* Implemented `RemoteGraph`, `RemoteConnection`, and `RemoteStrategy`.
* Added validation to `GryoMapper` Kryo identifiers before construction to prevent accidental duplicates.
* Added `GraphStep.addIds()` which is useful for `HasContainer` "fold ins."
* Added a static `GraphStep.processHashContainerIds()` helper for handling id-based `HasContainers`.
* `GraphStep` implementations should have `g.V().hasId(x)` and `g.V(x)` compile equivalently. *(breaking)*
* Optimized `ExpandableStepIterator` with simpler logic and increased the likelihood of bulking.
* Optimized `TraverserRequirement` calculations.
* `Step.addStart()` and `Step.addStarts()` now take `Traverser.Admin<S>` and `Traverser.Admin<S>`, respectively. *(breaking)*
* `Step.processNextStart()` and `Step.next()` now return `Traverser.Admin<E>`. *(breaking)*
* `Traversal.addTraverserRequirement()` method removed. *(breaking)*
* Fixed a `hashCode()` bug in `OrderGlobalStep` and `OrderLocalStep`.
* Added `OrderLimitStrategy` which will ensure that partitions are limited before being merged in OLAP.
* `ComparatorHolder` now separates the traversal from the comparator. *(breaking)*
* Bumped to Apache Spark 1.6.1.
* If no Spark serializer is provided then `GryoSerializer` is the default, not `JavaSerializer`.
* Added `Operator.sumLong` as a optimized binary operator intended to be used by `Memory` reducers that know they are dealing with longs.
* Traversers from `ComputerResultStep` are no longer attached. Attaching is only used in TinkerPop's test suite via `System.getProperties()`.
* Fixed a `hashCode()`/`equals()` bug in `MessageScope`.
* Fixed a severe `Traversal` cloning issue that caused inconsistent `TraversalSideEffects`.
* `TraversalSideEffects` remain consistent and usable across multiple chained OLAP jobs.
* Added `MemoryTraversalSideEffects` which wraps `Memory` in a `TraversalSideEffects` for use in OLAP.
* `TraversalSideEffects` are now fully functional in OLAP save that an accurate global view is possible at the start of an iteration (not during).
* Updated the `TraversalSideEffects` API to support registered reducers and updated `get()`-semantics. *(breaking)*
* Split existing `profile()` into `ProfileStep` and `ProfileSideEffectStep`.
* The `profile()`-step acts like a reducing barrier and emits `TraversalMetrics` without the need for `cap()`. *(breaking)*
* Added `LocalBarrier` interface to allow traversers to remain distributed during an iteration so as to reduce cluster traffic.
* Added `NoOpBarrierStep` as a `LocalBarrier` implementation of `LambdaCollectingBarrierStep(noOp)`.
* `AggregateStep` implements `LocalBarrier` and thus, doesn't needlessly communicate its barrier traversers.
* Fixed an OLAP-based `Barrier` synchronization bug.
* Fixed a semantic bug in `BranchStep` (and inheriting steps) where barriers reacted locally. *(breaking)*
* Added `MemoryComputeKey` for specification of `Memory` keys in `VertexProgram`. *(breaking)*
* Added `VertexComputeKey` for specification of vertex compute properties in `VertexProgram`. *(breaking)*
* Added `and`, `or`, and `addAll` to `Operator`.
* `Memory` API changed to support setting and adding values for reduction. *(breaking)*
* `Memory` keys can be marked as broadcast and only those values are sent to workers on each iterator.
* `Memory` keys can be marked transient and thus deleted at the end of the OLAP job.
* Vertex compute keys can be marked transient and thus deleted at the end of the OLAP job.
* `VertexProgram` API changed to support `MemoryComputeKey` and `VertexComputeKey`. *(breaking)*
* `TraversalVertexProgram` able to execute OLAP and OLTP traversal sections dynamically within the same job.
* Removed `FinalGet` interface as all post processing of reductions should be handled by the reducing step explicitly. *(breaking)*
* Simplified all `SupplyingBarrierStep` implementations as they no longer require `MapReduce` in OLAP.
* Simplified all `CollectingBarrierStep` implementations as they no longer require `MapReduce` in OLAP.
* Simplified all `ReducingBarrierStep` implementations as they no longer require `MapReduce` in OLAP.
* All steps in OLAP that used `MapReduce` now use `Memory` to do their reductions which expands the list of legal traversals.
* `GroupStep` simplified with `GroupHelper.GroupMap` no longer being needed. Related to the removal of `FinalGet`.
* OLAP side-effects that are no longer generated by `MapReduce` are simply stored in `ComputerResult.Memory` w/ no disk persistence needed. *(breaking)*
* Added `Generate` step interface which states that there could be a final generating phase to a side-effect or reduction (e.g. `GroupStep`).
* `Barrier` step interface is now the means by which non-parallel steps communicate with their counterparts in OLAP.
* Added `MemoryComputing` step interface which states that the step uses `MemoryComputeKeys` for its computation in OLAP.
* Added `PeerPressureVertexProgramStep` and `GraphTraversal.peerPressure()`.
* Added `PureTraversal` for handling pure and compiled versions of a `Traversal`. Useful in OLAP.
* Added `ScriptTraversal` which allows for delayed compilation of script-based `Traversals`.
* Simplified `VertexProgram` implementations with a `PureTraversal`-model and deprecated `ConfigurationTraversal`.
* Simplified script-based `Traversals` via `ScriptTraversal` and deprecated `TraversalScriptFunction` and `TraversalScriptHelper`.
* Added `TimesModulating` interface which allows the `Step` to decide how a `times()`-modulation should be handled.
* Added `ByModulating` interface which allows the `Step` to decide how a `by()`-modulation should be handled. *(breaking)*
* Simplified the `by()`-modulation patterns of `OrderGlobalStep` and `OrderLocalStep`.
* Added `GraphComputerTest.shouldSupportPreExistingComputeKeys()` to ensure existing compute keys are "revived." *(breaking)*
* Added `GraphComputerTest.shouldSupportJobChaining()` to ensure OLAP jobs can be linearly chained. *(breaking)*
* Fixed a bug in both `SparkGraphComputer` and `GiraphGraphComputer` regarding source data access in job chains.
* Expanded job chaining test coverage for `GraphComputer` providers.
* Added `TraversalHelper.onGraphComputer(traversal)`.
* `MapReduce.map()` no longer has a default implementation. This method must be implemented. *(breaking)*
* `TraversalVertexProgram` can work without a `GraphStep` start.
* Added `PageRankVertexProgramStep` and `GraphTraversal.pageRank()`.
* Added `TraversalVertexProgramStep` to support OLAP traversal job chaining.
* Added `VertexProgramStrategy` which compiles multiple OLAP jobs into a single traversal.
* Simplified the comparator model in `OrderGlobalStep` and `OrderLocalStep`.
* Refactored `TraversalSource` model to allow fluent-method construction of `TraversalSources`.
* Deprecated the concept of a `TraversalSource.Builder`.
* Removed the concept of a `TraversalEngine`. All `Traversal` modulations are now mediated by `TraversalStrategies`. *(breaking)*
* Added `SideEffectStrategy` for registering sideEffects in a spawned `Traversal`.
* Added `SackStrategy` for registering a sack for a spawned `Traversal`.
* Added `RequirementsStrategy` and `RequirementsStep` for adding dynamic `TraverserRequirements` to a `Traversal`.
* Removed `EngineDependentStrategy`.
* Renamed step interface `EngineDependent` to `GraphComputing` with method `onGraphComputer()`. *(breaking)*
* Cleaned up various `TraversalStrategy` tests now that `TraversalEngine` no longer exists.
* Added `GraphFilter` to support filtering out vertices and edges that won't be touched by an OLAP job.
* Added `GraphComputer.vertices()` and `GraphComputer.edges()` for `GraphFilter` construction. *(breaking)*
* `SparkGraphComputer`, `GiraphGraphComputer`, and `TinkerGraphComputer` all support `GraphFilter`.
* Added `GraphComputerTest.shouldSupportGraphFilter()` which verifies all filtered graphs have the same topology.
* Added `GraphFilterAware` interface to `hadoop-gremlin/` which tells the OLAP engine that the `InputFormat` handles filtering.
* `GryoInputFormat` and `ScriptInputFormat` implement `GraphFilterAware`.
* Added `GraphFilterInputFormat` which handles graph filtering for `InputFormats` that are not `GraphFilterAware`.
* Fixed a bug in `TraversalHelper.isLocalStarGraph()` which allowed certain illegal traversals to pass.
* Added `TraversalHelper.isLocalProperties()` to verify that the traversal does not touch incident edges.
* `GraphReader` I/O interface now has `Optional<Vertex> readGraph(InputStream, GraphFilter)`. Default `UnsupportedOperationException`.
* `GryoReader` does not materialize edges that will be filtered out and this greatly reduces GC and load times.
* Created custom `Serializers` for `SparkGraphComputer` message-passing classes which reduce graph sizes significantly.

==== Bugs

* TINKERPOP-951 Barrier steps provide unexpected results in Gremlin OLAP
* TINKERPOP-1057 GroupSideEffectStep doesn't use provided maps
* TINKERPOP-1103 Two objects fighting for local variable name in Gremlin Console *(breaking)*
* TINKERPOP-1149 TraversalXXXSteps Aren't Providing SideEffects
* TINKERPOP-1181 select(Column) should not use a LambdaMapStep
* TINKERPOP-1188 Semantics of BarrierSteps in TraversalParent global traversals is wrong. *(breaking)*
* TINKERPOP-1194 explain() seems broken
* TINKERPOP-1217 Repeated Logging of "The HadoopPools has not been initialized, using the default pool"

==== Improvements

* TINKERPOP-570 [Proposal] Provide support for OLAP to OLTP to OLAP to OLTP
* TINKERPOP-575 Implement RemoteGraph
* TINKERPOP-813 [Proposal] Make the Gremlin Graph Traversal Machine and Instruction Set Explicit
* TINKERPOP-872 Remove GroupCountStep in favor of new Reduce-based GroupStep
* TINKERPOP-890 Remove the concept of branch/ package. *(breaking)*
* TINKERPOP-958 Improve usability of .profile() step.
* TINKERPOP-962 Provide "vertex query" selectivity when importing data in OLAP. *(breaking)*
* TINKERPOP-968 Add first class support for an optional traversal
* TINKERPOP-971 TraversalSource should be fluent like GraphComputer *(breaking)*
* TINKERPOP-1016 Replace junit-benchmarks with JMH
* TINKERPOP-1021 Deprecate Order.valueIncr, Order.valueDecr, Order.keyIncr, and Order.keyDecr *(breaking)*
* TINKERPOP-1032 Clean up the conf/hadoop configurations
* TINKERPOP-1034 Bump to support Spark 1.5.2
* TINKERPOP-1069 Support Spark 1.6.0
* TINKERPOP-1082 INPUT_RDD and INPUT_FORMAT are bad, we should just have one key.
* TINKERPOP-1112 Create GryoSerializers for the Spark Payload classes.
* TINKERPOP-1121 FileSystemStorage needs to be smart about /.
* TINKERPOP-1132 Messenger.receiveMessages() Iterator should .remove().
* TINKERPOP-1140 TraversalVertexProgramStep in support of OLAP/OLTP conversions.
* TINKERPOP-1153 Add ByModulating and TimesModulating interfaces.
* TINKERPOP-1154 Create a ScriptTraversal which is Serializable and auto-compiles.
* TINKERPOP-1162 Add VertexProgram.getTransientComputeKeys() for removing scratch-data. *(breaking)*
* TINKERPOP-1163 GraphComputer's can have TraversalStrategies.
* TINKERPOP-1164 ReducingBarriersSteps should use ComputerMemory, not MapReduce.
* TINKERPOP-1166 Add Memory.reduce() as option to Memory implementations. *(breaking)*
* TINKERPOP-1173 If no Serializer is provided in Configuration, use GryoSerializer by default (Spark)
* TINKERPOP-1180 Add more optimized binary operators to Operator.
* TINKERPOP-1192 TraversalSideEffects should support registered reducers (binary operators).
* TINKERPOP-1193 Add a LocalBarrier interface.
* TINKERPOP-1199 Use "MicroMetrics" as the mutator of the TraversalMetrics.
* TINKERPOP-1206 ExpandableIterator can take a full TraverserSet at once -- Barriers.
* TINKERPOP-1209 ComparatorHolder should returns a Pair<Traversal,Comparator>. *(breaking)*
* TINKERPOP-1210 Provide an OrderLimitStep as an optimization.
* TINKERPOP-1219 Create a test case that ensures the provider's compilation of g.V(x) and g.V().hasId(x) is identical *(breaking)*
* TINKERPOP-1222 Allow default GraphComputer configuration
* TINKERPOP-1223 Allow jars in gremlin.distributedJars to be read from HDFS
* TINKERPOP-1225 Do a "rolling reduce" for GroupXXXStep in OLAP.
* TINKERPOP-1227 Add Metrics for the TraversalOpProcessor
* TINKERPOP-1234 program() step that takes arbitrary vertex programs
* TINKERPOP-1236 SelectDenormalizationStrategy for select().by(starGraph) in OLAP.
* TINKERPOP-1237 ProjectMap: For the Love of Die Faterland
* TINKERPOP-1238 Re-use Client instances in RemoteGraph tests

== TinkerPop 3.1.0 (A 187 On The Undercover Gremlinz)

image::https://raw.githubusercontent.com/apache/tinkerpop/master/docs/static/images/gremlin-gangster.png[width=185]

[[release-3-1-8]]
=== TinkerPop 3.1.8 (Release Date: August 21, 2017)

* Fixed a `MessageScope` bug in `TinkerGraphComputer`.
* Fixed a bug in `BigDecimal` divisions in `NumberHelper` that potentially threw an `ArithmeticException`.
* Non-deserializable exceptions no longer added to ScriptRecordReader IOExceptions.

==== Bugs

* TINKERPOP-1519 TinkerGraphComputer doesn't handle multiple MessageScopes in single iteration
* TINKERPOP-1736 Sack step evaluated by Groovy interprets numbers in an unexpected way
* TINKERPOP-1754 Spark can not deserialise some ScriptRecordReader parse exceptions

[[release-3-1-7]]
=== TinkerPop 3.1.7 (Release Date: June 12, 2017)

* Configured Modern and The Crew graphs to work with a integer `IdManager` when `TinkerFactory.createXXX()` is called.
* Added XSLT transform option to convert TinkerPop 2.x GraphML to 3.x GraphML.
* Added validation to `StarVertexProperty`.
* Bumped to Jackson 2.8.7.
* Fixed `EventStrategy` so that newly added properties trigger events with the name of the key that was added.
* Drop use of jitpack for the jbcrypt artifact - using the official one in Maven Central.
* Bumped to Groovy 2.4.11.

==== Improvements

* TINKERPOP-1504 MutationListener doesn't provide property key on property additions
* TINKERPOP-1608 TP2-to-TP3 GraphML XSLT
* TINKERPOP-1633 Use org.mindrot:jbcrypt v0.4
* TINKERPOP-1645 Bump to Groovy 2.4.9
* TINKERPOP-1654 Upgrade to jackson-databind 2.8.6+ in gremlin-shaded
* TINKERPOP-1659 Docker build should use maven settings.xml
* TINKERPOP-1664 StarVertexProperty#property should throw an NPE if the value is null

[[release-3-1-6]]
=== TinkerPop 3.1.6 (Release Date: February 3, 2017)

* Fixed bug in `IncidentToAdjacentStrategy`, it was missing some invalidating steps.
* Returned a confirmation on session close from Gremlin Server.
* Use non-default port for running tests on Gremlin Server.
* Fully shutdown metrics services in Gremlin Server on shutdown.
* Deprecated `tryRandomCommit()` in `AbstractGremlinTest` - the annotation was never added in 3.1.1, and was only deprecated via javadoc.
* Minor fixes to various test feature requirements in `gremlin-test`.
* Allow developers to pass options to `docker run` with TINKERPOP_DOCKER_OPTS environment variable

==== Bugs

* TINKERPOP-1493 Groovy project doesn't build on Windows
* TINKERPOP-1545 IncidentToAdjacentStrategy is buggy

==== Improvements

* TINKERPOP-1538 Gremlin Server spawned by test suites should use a different port
* TINKERPOP-1544 Return a confirmation of session close
* TINKERPOP-1556 Allow Hadoop to run on IPv6 systems
* TINKERPOP-1557 Improve docker build time with this one weird trick!
* TINKERPOP-1598 Bump to Grovy 2.4.8

[[release-3-1-5]]
=== TinkerPop 3.1.5 (Release Date: October 17, 2016)

* Improved handling of `Cluster.close()` and `Client.close()` to prevent the methods from hanging.
* Fixed a bug in `NotStep` where child requirements were not being analyzed.
* Fixed output redirection and potential memory leak in `GremlinGroovyScriptEngine`.
* Corrected naming of `g_withPath_V_asXaX_out_out_mapXa_name_it_nameX` and `g_withPath_V_asXaX_out_mapXa_nameX` in `MapTest`.
* Improved session cleanup when a close is triggered by the client.
* Removed the `appveyor.yml` file as the AppVeyor build is no longer enabled by Apache Infrastructure.
* Fixed TinkerGraph which was not saving on `close()` if the path only consisted of the file name.
* Fixed a bug in `RangeByIsCountStrategy` which didn't use the `NotStep` properly.

==== Bugs

* TINKERPOP-1158 gremlin.sh -v emits log4j initialization errors
* TINKERPOP-1391 issue with where filter
* TINKERPOP-1442 Killing session should make better attempt to cleanup
* TINKERPOP-1451 TinkerGraph persistence cannot handle a single file name as the graph location
* TINKERPOP-1467 Improve close() operations on the Java driver
* TINKERPOP-1478 Propogate ScriptEngine fixes from groovy to GremlinGroovyScriptEngine
* TINKERPOP-1512 gremlin-server-classic.yaml is broken

==== Improvements

* TINKERPOP-927 bin/publish-docs.sh should only upload diffs.
* TINKERPOP-1264 Improve BLVP docs
* TINKERPOP-1477 Make DependencyGrabberTest an integration test

[[release-3-1-4]]
=== TinkerPop 3.1.4 (Release Date: September 6, 2016)

* Improved the error provided by a client-side session if no hosts were available.
* Fixed a bug in `PropertiesTest` which assumed long id values.
* Fixed a bug in `StarGraph` around self-edges.
* Fixed a potential leak of a `ReferenceCounted` resource in Gremlin Server.
* Renamed distributions to make the prefix "apache-tinkerpop-" as opposed to just "apache-".
* Fixed a problem (previously thought resolved on 3.1.3) causing Gremlin Server to lock up when parallel requests were submitted on the same session if those parallel requests included a script that blocked indefinitely.
* Fixed bug in `TailGlobalStep` where excess bulk was not accounted for correctly.

==== Bugs

* TINKERPOP-1350 Server locks when submitting parallel requests on session
* TINKERPOP-1375 Possible ByteBuf leak for certain transactional scenarios
* TINKERPOP-1377 Closing a remote in "console mode" has bad message
* TINKERPOP-1379 unaccounted excess in TailGlobalStep
* TINKERPOP-1397 StarVertex self edge has buggy interaction with graph filters
* TINKERPOP-1419 Wrong exception when a SessionedClient is initialized with no available host

==== Improvements

* TINKERPOP-989 Default documentation should be reference/index.html
* TINKERPOP-1376 Rename TinkerPop artifacts
* TINKERPOP-1413 PropertiesTest#g_V_hasXageX_propertiesXnameX assumes that ids are longs
* TINKERPOP-1416 Write Gremlin Server log files somewhere during doc generation
* TINKERPOP-1418 CoreTraversalTests depend on missing functionality

[[release-3-1-3]]
=== TinkerPop 3.1.3 (Release Date: July 18, 2016)

* Fixed bug in `SubgraphStep` where features were not being checked properly prior to reading meta-properties.
* Ensured calls to `Result.hasNext()` were idempotent.
* Avoid hamcrest conflict by using mockito-core instead of mockito-all dependency in `gremlin-test`.
* Fixed bug in `GremlinExecutor` causing Gremlin Server to lock up when parallel requests were submitted on the same session if those parallel requests included a script that blocked indefinitely.
* Changed `GremlinExecutor` timeout scheduling so that the timer would not start until a time closer to the actual start of script evaluation.
* Fixed bug in `SubgraphStrategy` where step labels were not being propogated properly to new steps injected by the strategy.
* Fix incorrect test `FeatureRequirement` annotations.
* Defaulted to `Edge.DEFAULT` if no edge label was supplied in GraphML.
* Fixed bug in `IoGraphTest` causing IllegalArgumentException: URI is not hierarchical error for external graph implementations.
* Fixed bug in `GremlinGroovyScriptEngineFileSandboxTest` resource loading
* Improved `TinkerGraph` performance when iterating vertices and edges.
* Fixed a bug where timeout functions provided to the `GremlinExecutor` were not executing in the same thread as the script evaluation.
* Fixed a bug in the driver where many parallel requests over a session would sometimes force a connection to close and replace itself.
* Graph providers should no longer rely on the test suite to validate that hyphens work for property keys.
* Optimized a few special cases in `RangeByIsCountStrategy`.
* Added more "invalid" variable bindings to the list used by Gremlin Server to validate incoming bindings on requests.
* Fixed a bug where the `ConnectionPool` in the driver would not grow with certain configuration options.
* Fixed a bug where pauses in Gremlin Server writing to an overtaxed client would generate unexpected `FastNoSuchElementException` errors.
* Named the thread pool used by Gremlin Server sessions: "gremlin-server-session-$n".
* Fixed a bug in `BulkSet.equals()` which made itself apparent when using `store()` and `aggregate()` with labeled `cap()`.
* Fixed a bug where `Result.one()` could potentially block indefinitely under certain circumstances.
* Ensured that all asserts of vertex and edge counts were being applied properly in the test suite.
* Fixed bug in `gremlin-driver` where certain channel-level errors would not allow the driver to reconnect.
* `SubgraphStep` now consults the parent graph features to determine cardinality of a property.
* Use of `Ctrl-C` in Gremlin Console now triggers closing of open remotes.
* Bumped SLF4J to 1.7.21 as previous versions suffered from a memory leak.
* Fixed a bug in `Neo4jGraphStepStrategy` where it wasn't defined properly as a `ProviderOptimizationStrategy`.
* Renamed `AndTest.get_g_V_andXhasXage_gt_27X__outE_count_gt_2X_name` to `get_g_V_andXhasXage_gt_27X__outE_count_gte_2X_name` to match the traversal being tested.
* Fixed a self-loop bug in `StarGraph`.
* Added configuration option for disabling `:remote` timeout with `:remote config timeout none`.
* Added `init-tp-spark.sh` to Gremlin Console binary distribution.
* Fixed bug where use of `:x` in a Gremlin Console initialization script would generate a stack trace.
* Added configuration options to Gremlin Driver and Server to override the SSL configuration with an `SslContext`.
* Added driver configuration settings for SSL: `keyCertChainFile`, `keyFile` and `keyPassword`.
* Fixed bug where transaction managed sessions were not properly rolling back transactions for exceptions encountered during script evaluation.
* Fixed bug in `:uninstall` command if the default `/ext` directory was not used.
* Added support to Gremlin Driver to allow either plain text or GSSAPI SASL authentication allowing the client to pass the SASL mechanism in the request.
* Improved dryRun functionality for the docs processor. It's now possible to dry run (or full run) only specific files.
* Added precompile of `ScriptInputFormat` scripts to `ScriptRecordReader` to improve performance.

==== Bugs

* TINKERPOP-906 Install plugin always fails after first unresolved dependency
* TINKERPOP-1088 Preserve Cardinality in Subgraph
* TINKERPOP-1092 Gremlin Console init script with :x throws exception
* TINKERPOP-1139 [Neo4JGraph] GraphTraversal with SubgraphStrategy removes addLabelStep (as("b"))
* TINKERPOP-1196 Calls to Result.one() might block indefinitely
* TINKERPOP-1215 Labeled a SideEffectCapStep cause problems.
* TINKERPOP-1242 ScriptEngineTest randomly hangs indefinately.
* TINKERPOP-1257 Bad SackTest variable use.
* TINKERPOP-1265 Managed Session Eval Exceptions Rollback
* TINKERPOP-1272 Gremlin Console distribution needs bin/init-tp-spark.sh
* TINKERPOP-1284 StarGraph does not handle self-loops correctly.
* TINKERPOP-1300 Many asserts around vertex/edge counts on graphs not applied
* TINKERPOP-1317 IoGraphTest throws error: URI is not hierarchical
* TINKERPOP-1318 java.lang.NoSuchMethodError: org/hamcrest/Matcher.describeMismatch
* TINKERPOP-1319 several FeatureRequirement annotations are incorrect in gremlin-test
* TINKERPOP-1320 GremlinGroovyScriptEngineFileSandboxTest throws error: URI is not hierarchical
* TINKERPOP-1324 Better error for invalid args to addV()
* TINKERPOP-1350 Server locks when submitting parallel requests on session
* TINKERPOP-1351 Number of connections going beyond the pool max size
* TINKERPOP-1352 Connection Pool doesn't always grow
* TINKERPOP-1359 Exception thrown when calling subgraph() on Neo4jGraph
* TINKERPOP-1360 intermittent error in spark-gremlin integration test

==== Improvements

* TINKERPOP-939 Neo4jGraph should support HighAvailability (Neo4jHA).
* TINKERPOP-1003 Setting up latest/current links for bins and docs.
* TINKERPOP-1020 Provide --dryRun selectivity for "half publishing" docs.
* TINKERPOP-1063 TinkerGraph performance enhancements
* TINKERPOP-1229 More Descriptive Messaging for :remote console
* TINKERPOP-1260 Log for validate-distribution.sh
* TINKERPOP-1263 Pass SASL mechanism name through with initial SASL response
* TINKERPOP-1267 Configure Console for no timeout on remote requests
* TINKERPOP-1269 More SSL settings for driver
* TINKERPOP-1295 Precompile ScriptInputFormat scripts once during initialization of ScriptRecordReader
* TINKERPOP-1301 Provide Javadoc for ScriptInput/OutputFormat's
* TINKERPOP-1302 Ctrl-C should kill open remotes in Console
* TINKERPOP-1312 .count().is(0) is not properly optimized
* TINKERPOP-1314 Improve error detection in docs preprocessor
* TINKERPOP-1354 Include all static enum imports in request validation for bindings *(breaking)*

[[release-3-1-2-incubating]]
=== TinkerPop 3.1.2 (Release Date: April 8, 2016)

* Fixed two `NullPointerException`-potential situations in `ObjectWritable`.
* Provided Docker script that allows the execution of several build tasks within a Docker container.
* Added a per-request `scriptEvaluationTimeout` option to the Gremlin Server protocol.
* Changed `DriverRemoteAcceptor` to send scripts as multi-line.
* Fixed a bug in `gremlin-driver` where connections were not returning to the pool after many consecutive errors.
* Fixed a bug where `tree()` did not serialize into GraphSON.
* Bumped to SLF4j 1.7.19.
* Bumped to Apache Hadoop 2.7.2.
* Fixed a bug in `gremlin-driver` where a really fast call to get a `Future` to wait for a result might not register an error raised from the server.
* Fixed a severe bug where `LP_O_OB_P_S_SE_SL_Traverser` was not registered with `GryoMapper`.
* The future from `GremlinExecutor.eval()` is completed after the entire evaluation lifecyle is completed.
* Spark `Memory` uses `collect().iterator()` instead of `toLocalIterator()` to reduce noise in Spark UI.
* Added the `:remote console` option which flips the Gremlin Console into a remote-only mode where all script evaluation is routed to the currently configured remote, which removes the need to use the `:>` command.
* Added `allowRemoteConsole()` to the `RemoteAcceptor` interface.
* The `:remote` for `tinkerpop.server` now includes an option to establish the connection as a "session".
* Provided an implementation for calls to `SessionedClient.alias()`, which formerly threw an `UnsupportedOperationException`.
* Bumped to commons-collections 3.2.2.
* Fixed a bug where `OrderGlobalStep` and `OrderLocalStep` were not incorporating their children's traverser requirements.
* Fixed a compilation bug in `TraversalExplanation`.
* Fixed bug where a session explicitly closed was being closed again by session expiration.
* Improved the recovery options for `gremlin-driver` after failed requests to Gremlin Server.
* Added `maxWaitForSessionClose` to the settings for `gremlin-driver`.
* Bumped to Netty 4.0.34.Final.
* Added "interpreter mode" for the `ScriptEngine` and Gremlin Server which allows variables defined with `def` or a type to be recognized as "global".
* Bumped to Apache Groovy 2.4.6.
* Added the `gremlin-archetype-server` archetype that demonstrates
* Added the `gremlin-archetype-tinkergraph` archetype that demonstrates a basic project that uses TinkerGraph.
* Added `gremlin-archetype` module to house TinkerPop "examples".
* Fixed a condition where `ConnectionPool` initialization in the driver would present a `NullPointerException` on initialization if there were errors constructing the pool in full.
* Fixed a bug in the round-robin load balancing strategy in the driver would waste requests potentially sending messages to dead hosts.
* Added new Provider Documentation book - content for this book was extracted from the reference documentation.
* Fixed a bug where multiple "close" requests were being sent by the driver on `Client.close()`.
* Fixed an `Property` attach bug that shows up in serialization-based `GraphComputer` implementations.
* Fixed a pom.xml bug where Gremlin Console/Server were not pulling the latest Neo4j 2.3.2.
* Fixed bug in "round robin" load balancing in `gremlin-driver` where requests were wrongly being sent to the same host.
* Prevented the spawning of unneeded reconnect tasks in `gremlin-driver` when a host goes offline.
* Fixed bug preventing `gremlin-driver` from reconnecting to Gremlin Server when it was restarted.
* Better handled errors that occurred on commits and serialization in Gremlin Server to first break the result iteration loop and to ensure commit errors were reported to the client.
* Added GraphSON serializers for the `java.time.*` classes.
* Improved the logging of the Gremlin Server REST endpoint as it pertained to script execution failures.
* `TraversalExplanation` is now `Serializable` and compatible with GraphSON and Gryo serialization.
* Fixed a problem with global bindings in Gremlin Server which weren't properly designed to handle concurrent modification.
* Deprecated `ScriptElementFactory` and made the local `StarGraph` globally available for ``ScriptInputFormat``'s `parse()` method.
* Improved reusability of unique test directory creation in `/target` for `AbstractGraphProvider`, which was formerly only available to Neo4j, by adding `makeTestDirectory()`.
* Optimized memory-usage in `TraversalVertexProgram`.
* `Graph` instances are not merely "closed" at the end of tests, they are "cleared" via `GraphProvider.clear()`, which should in turn cleans up old data for an implementation.
* Expanded the Gremlin Server protocol to allow for transaction management on in-session requests and updated the `gremlin-driver` to take advantage of that.
* Greatly reduced the amount of objects required in OLAP for the `ReducingBarrierStep` steps.
* Improved messages for the different distinct "timeouts" that a user can encounter with Gremlin Server.

==== Bugs

* TINKERPOP-1041 StructureStandardTestSuite has file I/O issues on Windows
* TINKERPOP-1105 SparkGraphComputer / Null Pointer Exceptions for properties traversals
* TINKERPOP-1106 Errors on commit in Gremlin Server don't register as exception on driver
* TINKERPOP-1125 RoundRobin load balancing always uses the second Host when size = 2
* TINKERPOP-1126 A single Host spawns many reconnect tasks
* TINKERPOP-1127 client fails to reconnect to restarted server
* TINKERPOP-1146 IoTest are not clearing the db after the test run
* TINKERPOP-1148 ConcurrentModificationException with bindings in Gremlin Server
* TINKERPOP-1150 Update pom file dependencies to work with Neo4j 2.3.2
* TINKERPOP-1159 Client sends multiple session close messages per host
* TINKERPOP-1168 Switch plugins in docs preprocessor
* TINKERPOP-1172 Reconnect to Gremlin Server previously marked as dead
* TINKERPOP-1175 Anonymous traversals can't be explained
* TINKERPOP-1184 Sessions not being closed properly
* TINKERPOP-1216 OrderStep or O_Traverser is broken
* TINKERPOP-1239 Excessive continual failure for requests can cause TimeoutException in driver
* TINKERPOP-1245 Gremlin shell starts incorrectly on OS X due to awk difference
* TINKERPOP-1251 NPE in ObjectWritable.toString
* TINKERPOP-1252 Failed Neo4j transaction can leave Neo4jTransaction in inconsistent state

==== Improvements

* TINKERPOP-732 gremlin-server GraphSON serializer issue with tree()
* TINKERPOP-916 Develop a better "simple" driver for testing and example purposes
* TINKERPOP-937 Extract the implementations sections of the primary documentation to its own book
* TINKERPOP-956 Connection errors tend to force a complete close of the channel
* TINKERPOP-1039 Enable auto-commit for session'd requests.
* TINKERPOP-1068 Bump to support jbcrypt-0.4m.jar
* TINKERPOP-1080 Bump Netty version - 4.0.34.Final
* TINKERPOP-1085 Establish TinkerPop "example" projects
* TINKERPOP-1096 Support aliasing for sessions in Gremlin Server
* TINKERPOP-1097 Gremlin Console supporting sessions
* TINKERPOP-1107 Provide a way to support global variables with sandboxing enabled
* TINKERPOP-1109 Make Gremlin Console better suited for system level installs
* TINKERPOP-1131 TraversalVertexProgram traverser management is inefficient memory-wise.
* TINKERPOP-1135 Improve GraphSON representation of java.time.* classes
* TINKERPOP-1137 Deprecate ScriptElementFactory and make star graph globally available
* TINKERPOP-1138 Improve messaging on server timeouts
* TINKERPOP-1147 Add serialization for TraversalExplanation
* TINKERPOP-1160 Add timeout configuration for time to wait for connection close
* TINKERPOP-1165 Tooling Support: Compile with -parameters
* TINKERPOP-1176 Bump Groovy version - 2.4.6
* TINKERPOP-1177 Improve documentation around Spark's storage levels
* TINKERPOP-1197 Document Gremlin Server available metrics
* TINKERPOP-1198 Bump commons-collections to 3.2.2
* TINKERPOP-1213 missing docs for has(label, key, value)
* TINKERPOP-1218 Usage of toLocalIterator Produces large amount of Spark Jobs

[[release-3-1-1-incubating]]
=== TinkerPop 3.1.1 (Release Date: February 8, 2016)

* Made `GryoRecordReader` more robust to 0 byte record splits.
* Fixed a constructor/serialization bug in `LP_O_OB_S_SE_SL_Traverser`.
* Added a lazy iterator, memory safe implementation of MapReduce to `SparkGraphComputer`.
* Added `MapReduce.combine()` support to `SparkGraphComputer`.
* Bumped to Neo4j 2.3.2.
* Fixed Java comparator contract issue around `Order.shuffle`.
* Optimized a very inefficient implementation of `SampleLocalStep`.
* Reduced the complexity and execution time of all `AbstractLambdaTraversal` instances.
* `DefaultTraversal` has a well defined `hashCode()` and `equals()`.
* Added serializers to Gryo for `java.time` related classes.
* Integrated `NumberHelper` in `SackFunctions`.
* Deprecated `VertexPropertyFeatures.supportsAddProperty()` which effectively was a duplicate of `VertexFeatures.supportsMetaProperties`.
* The Spark persistence `StorageLevel` can now be set for both job graphs and `PersistedOutputRDD` data.
* Added to the list of "invalid binding keys" allowed by Gremlin Server to cover the private fields of `T` which get exposed in the `ScriptEngine` on static imports.
* Added `BulkDumperVertexProgram` that allows to dump a whole graph in any of the supported IO formats (GraphSON, Gryo, Script).
* Fixed a bug around duration calculations of `cap()`-step during profiling.
* It is possible to completely avoid using HDFS with Spark if `PersistedInputRDD` and `PersistedOutpuRDD` are leveraged.
* `InputRDD` and `OutputRDD` can now process both graphs and memory (i.e. sideEffects).
* Removed Groovy specific meta-programming overloads for handling Hadoop `FileSystem` (instead, its all accessible via `FileSystemStorage`).
* Added `FileSystemStorage` and `SparkContextStorage` which both implement the new `Storage` API.
* Added `Storage` to the gremlin-core io-package which providers can implement to allow conventional access to data sources (e.g. `ls()`, `rm()`, `cp()`, etc.).
* Bumped to Spark 1.5.2.
* Bumped to Groovy 2.4.5.
* Added `--noClean` option in `bin/process-docs.sh` to prevent the script from cleaning Grapes and HDFS.
* Execute the `LifeCycle.beforeEval()` in the same thread that `eval()` is executed in for `GremlinExecutor`.
* Improved error handling of Gremlin Console initialization scripts to better separate errors in initialization script I/O versus execution of the script itself.
* Fixed a bug in `Graph.OptOut` when trying to opt-out of certain test cases with the `method` property set to "*".
* Added another `BulkLoader` implementation (`OneTimeBulkLoader`) that doesn't store temporary properties in the target graph.
* Added option to allow for a custom `ClassResolver` to be assigned to a `GryoMapper` instance.
* Fixed a `SparkGraphComputer` sorting bug in MapReduce that occurred when there was more than one partition.
* Added `strictTransactionManagement` to the Gremlin Server settings to indicate that the `aliases` parameter must be passed on requests and that transaction management will be scoped to the graphs provided in that argument.
* Fixed a `NullPointerException` bug in `PeerPressureVertexProgram` that occurred when an adjacency traversal was not provided.
* Standardized "test data directories" across all tests as generated by `TestHelper`.
* Fixed a bug in Gremlin Server where error messages were not always being passed back in the `statusMessage` field of the `ResponseMessage`.
* Added validation for parameter `bindings` to ensure that keys were `String` values.
* Improved Transaction Management consistency in Gremlin Server.
* Added `FileSandboxExtension` which takes a configuration file to white list methods and classes that can be used in `ScriptEngine` execution.
* Deprecated `SandboxExtension` and `SimpleSandboxExtension` in favor of `AbstractSandboxExtension` which provides better abstractions for those writing sandboxes.
* Fixed a long standing "view merge" issue requiring `reduceByKey()` on input data to Spark. It is no longer required.
* Added `Spark` static object to allow "file system" control of persisted RDDs in Spark.
* Added a Spark "job server" to ensure that persisted RDDs are not garbage collected by Spark.
* Improved logging control during builds with Maven.
* Fixed settings that weren't being passed to the Gremlin Driver `Cluster` through configuration file.
* `Column` now implements `Function`. The modulator `by(valueDecr)` can be replaced by `by(values,decr)` and thus, projection and order are separated.
* Added `InputRDDFormat` which wraps an `InputRDD` to make it accessible to Hadoop and not just Spark.
* Added `AbstractSparkTest` which handles closing `SparkContext` instances between tests now that we support persisted contexts.
* Fixed a serialization bug in `GryoSerializer` that made it difficult for graph providers to yield `InputRDDs` for `SparkGraphComputer`.
* `SparkGraphComputer` is now tested against Gryo, GraphSON, and `InputRDD` data sources.
* `HadoopElementIterator` (for Hadoop-Gremlin OLTP) now works for any `InputFormat`, not just `FileInputFormats`.
* Added `Traverser.Admin.getTags()` which are used to mark branches in a traversal (useful in `match()` and related future steps).
* Fixed the `Future` model for `GiraphGraphComputer` and `SparkGraphComputer` so that class loaders are preserved.
* Added support for arbitrary vertex ID types in `BulkLoaderVertexProgram`.
* Deprecated `credentialsDbLocation` from `SimpleAuthenticator` in Gremlin Server.
* `TinkerGraph` has "native" serialization in GraphSON, which enables it to be a return value from Gremlin Server.
* Improved the ability to embed Gremlin Server by providing a way to get the `ServerGremlinExecutor` and improve reusability of `AbstractEvalOpProcessor` and related classes.
* Added `Authenticator.newSaslNegotiator(InetAddress)` and deprecated the zero-arg version of that method.
* `ProfileStep` is now available off of `Traversal` via `profile()`. To be consistent with `Traversal.explain()`.
* If no comparator is provided to `order()`, `Order.incr` is assumed (previously, an exception occurred).
* Fixed various Gremlin-Groovy tests that assumed `toString()`-able ids.
* Split TinkerPop documentation into different directories.
* Added `explain()`-step which yields a `TraversalExplanation` with a pretty `toString()` detailing the compilation process.
* Fixed a traversal strategy ordering bug in `AdjacentToIncidentStrategy` and `IncidentToAdjacentStrategy`.
* Made a number of changes to improve traversal startup and execution performance.
* Added support for 'gremlin.tinkergraph.graphLocation' to accept a fully qualified class name that implements `Io.Builder` interface.

==== Bugs

* TINKERPOP-763 IsStep broken when profiling is enabled.
* TINKERPOP-972 Cluster::close does not shut down its executor
* TINKERPOP-973 BLVP shouldn't clear configuration properties
* TINKERPOP-976 Fail earlier if invalid version is supplied in validate-distribution.sh
* TINKERPOP-977 Dead link to traversal javadocs
* TINKERPOP-979 ComputerVerificationStrategy not picking up Order local traversal
* TINKERPOP-985 shouldPersistDataOnClose makes incorrect feature check
* TINKERPOP-990 Mixed types in VertexPropertyTest
* TINKERPOP-993 cyclicPath is not(simplePath)
* TINKERPOP-997 FeatureRequirementSet.SIMPLE should not require multi-property *(breaking)*
* TINKERPOP-1000 GremlinGroovyScriptEngineOverGraphTest failures
* TINKERPOP-1001 SugarLoaderPerformanceTest contains hardcoded vertex ids
* TINKERPOP-1002 Should rollback transaction after catching on close
* TINKERPOP-1006 Random error during builds: shouldReloadClassLoaderWhileDoingEvalInSeparateThread()
* TINKERPOP-1011 HadoopGraph can't re-attach when the InputFormat is not a FileInputFormat
* TINKERPOP-1012 BulkLoaderVertexProgram shouldn't assume vertex IDs of type Long
* TINKERPOP-1025 Solve SparkContext Persistence Issues with BulkLoaderVertexProgram
* TINKERPOP-1027 Merge view prior to writing graphRDD to output format/rdd
* TINKERPOP-1036 Support self-looping edges in IO
* TINKERPOP-1052 @Graph.OptOut causes Exception during Suite setup
* TINKERPOP-1060 LambdaRestrictionStrategy too restrictive
* TINKERPOP-1075 Profile duration of cap step seems broken.
* TINKERPOP-1083 Traversal needs a hashCode() and equals() definition.
* TINKERPOP-1089 Order.shuffle implementation is too fragile
* TINKERPOP-1119 LP_O_OB_S_SE_SL_Traverser doesn't have a protected constructor().

==== Improvements

* TINKERPOP-320 BulkDumperVertexProgram
* TINKERPOP-379 MessageScope.Local.setStaticMessage(M msg)
* TINKERPOP-824 Do we need runtime BigDecimal in more places?
* TINKERPOP-859 Provide a more general way to set log levels in plugins
* TINKERPOP-860 Bindings applied to the PluginAcceptor should appear to Gremlin Server
* TINKERPOP-886 Allow any GraphReader/Writer to be persistence engine for TinkerGraph
* TINKERPOP-891 Re-examine Sandboxing Abstractions
* TINKERPOP-912 Improve the ability to embed Gremlin Server with Channelizer injection
* TINKERPOP-928 Use directories to separate different books
* TINKERPOP-930 Tie Alias to Transaction Manager in Gremlin Server
* TINKERPOP-938 Add a "clear SNAPSHOT jars" section to the process-docs.sh.
* TINKERPOP-941 Improve error message for wrong order().by() arguments
* TINKERPOP-943 Warn if Gremlin Server is running prior to generating docs
* TINKERPOP-945 Exceptions should allow me to include root cause if/when available
* TINKERPOP-952 Include Cardinality.list example in VertexProperty section of main docs.
* TINKERPOP-954 Consistent test directory usage
* TINKERPOP-957 Improve speed of addV()
* TINKERPOP-964 Test XXXGraphComputer on a Hadoop2 cluster (non-pseudocluster).
* TINKERPOP-970 ProfileStep should be off Traversal, not GraphTraversal
* TINKERPOP-978 Native TinkerGraph Serializers for GraphSON
* TINKERPOP-981 Deprecate support for credentialsDbLocation in Gremlin Server Config
* TINKERPOP-982 valuesDecr, valuesIncr, keysDecr, and valuesDecr is lame.
* TINKERPOP-983 Provide a way to track open Graph instances in tests
* TINKERPOP-984 Use GraphProvider for id conversion in Groovy Environment test suite
* TINKERPOP-987 Use tinkerpop.apache.org URL in all documentation and homepage
* TINKERPOP-988 SparkGraphComputer.submit shouldn't use ForkJoinPool.commonPool
* TINKERPOP-992 Better support for schema driven Graphs in IO related tests
* TINKERPOP-994 Driver using deprecated Rebindings Still
* TINKERPOP-995 Add Authenticator.newSaslNegotiator(InetAddress)
* TINKERPOP-996 Please delete old releases from mirroring system
* TINKERPOP-998 Deprecate VertexPropertyFeatures.FEATURE_ADD_PROPERTY
* TINKERPOP-1009 Add a CAUTION to documentation about HadoopGraph and getting back elements
* TINKERPOP-1013 Traverser tags as a safer way of using path labels
* TINKERPOP-1018 Allow setting for maxContentLength to be set from yaml in driver
* TINKERPOP-1019 Convert println in test to SLF4j
* TINKERPOP-1022 Automatically warm up ops handlers
* TINKERPOP-1023 Add a spark variable in SparkGremlinPlugin like we do hdfs for HadoopGremlinPlugin
* TINKERPOP-1026 BVLP should store vertex IDs as String
* TINKERPOP-1033 Store sideEffects as a persisted RDD
* TINKERPOP-1035 Better Consistency in Gremlin Server Transaction Management
* TINKERPOP-1045 Client-Side Hangs when attempting to access a HashMap with Keys of type Integer
* TINKERPOP-1047 TinkerGraph GraphSON storage format broken
* TINKERPOP-1051 Add note in best practice docs about gremlin server heap setting
* TINKERPOP-1055 Gremlin Console FileNotFoundException can be misleading
* TINKERPOP-1062 Make LifeCycle beforeEval execute in same thread as eval operation
* TINKERPOP-1064 Allow a ClassResolver to be added to GryoMapper construction
* TINKERPOP-1065 Fix some typos and clarify some wording in the TinkerPop documentation
* TINKERPOP-1066 Add ioRegistries configuration to GraphSON MessageSerializer
* TINKERPOP-1067 Update Groovy to 2.4.5
* TINKERPOP-1072 Allow the user to set persistence options using StorageLevel.valueOf()
* TINKERPOP-1073 HadoopGraph toString() is weird for Spark PersitedRDD data.
* TINKERPOP-1086 Include gryo serializers for java.time related classes
* TINKERPOP-1087 Add has()/order() to FilterRankStrategy
* TINKERPOP-1093 Add Spark init.sh script and update dev documentation.
* TINKERPOP-1100 Look deeply into adding combine()-support in Spark MapReduce.
* TINKERPOP-1117 InputFormatRDD.readGraphRDD requires a valid gremlin.hadoop.inputLocation, breaking InputFormats (Cassandra, HBase) that don't need one

[[release-3-1-0-incubating]]
=== TinkerPop 3.1.0 (Release Date: November 16, 2015)

This release also includes changes from <<release-3-0-1-incubating, 3.0.1-incubating>> and <<release-3-0-2-incubating, 3.0.2-incubating>>.

* Fixed bug in Gryo and GraphSON (with embedded types) serialization for serialization of results returned from `Map.entrySet()`.
* `Transaction` settings for `onReadWrite` and `onClose` are now `ThreadLocal` in nature of standard transactions.
* Optimized `BulkLoaderVertexProgram`. It now uses `EventStrategy` to monitor what the underlying `BulkLoader` implementation does (e.g. whether it creates a new vertex or returns an existing).
* Integrated `NumberHelper` in `SumStep`, `MinStep`, `MaxStep` and `MeanStep` (local and global step variants).
* Gremlin Console remoting to Gremlin Server now supports a configuration option for assigning aliases.
* `CountMatchAlgorithm`, in OLAP, now biases traversal selection towards those traversals that start at the current traverser location to reduce message passing.
* Fixed a file stream bug in Hadoop OLTP that showed up if the streamed file was more than 2G of data.
* Added the ability to set thread local properties in `SparkGraphComputer` when using a persistent context.
* Bumped to Neo4j 2.3.0.
* Deprecated "rebindings" as an argument to Gremlin Server and replaced it with "aliases".
* Added `PersistedInputRDD` and `PersistedOutputRDD` which enables `SparkGraphComputer` to store the graph RDD in the context between jobs (no HDFS serialization required).
* Renamed the `public static String` configuration variable names of TinkerGraph (deprecated old variables).
* Added `GraphComputer.configure(key,value)` to allow engine-specific configurations.
* `GraphStep` is no longer in the `sideEffect`-package and is now in `map`-package (breaking change).
* Added support for mid-traversal `V()`-steps (`GraphStep` semantics updated).
* Fixed `Number` handling in `Operator` enums. Prior this change a lot of operations on mixed `Number` types returned a wrong result (wrong data type).
* Fixed a bug in Gremlin Server/Driver serializer where empty buffers were getting returned in certain cases.
* Renamed `ConjunctionX` to `ConnectiveX` because "conjunction" is assumed "and" (disjunction "or"), where "connective" is the parent concept.
* Removed `PathIdentityStep` as it was a hack that is now solved by `Traversal.Admin.addTraverserRequirement()`.
* Added `Traversal.Admin.addTraverserRequirement()` to allow a traversal strategy or source to add requirements (not only step determined anymore).
* Added `TraverserRequirement.ONE_BULK` to state the traverser does not handle bulk.
* Added `GraphTraversalSource.withBulk(boolean)` to enabled users to compute only using `bulk=1`.
* Gremlin Server supports Netty native transport on linux.
* Removed the need for `GFunction` (etc.) closure wrappers in Gremlin-Groovy as `as Function` can be used to convert closures accordingly.
* Added `SelectColumnStep` (`select(keys)` and `select(values)`). Deprecated `mapKeys()` and `mapValues()`.
* Renamed `gremlin.hadoop.graphInputRDD` and `gremlin.hadoop.graphOutputRDD` to `gremlin.spark.graphInputRDD` and `gremlin.spark.graphOutputRDD`, respectively.
* Fixed a bug in `FoldStep` around bulking. This could be a breaking change, but it is the correct semantics.
* Previous `group()`-behavior steps are accessible via the deprecated `groupV3d0()`-steps.
* `GroupStep` and `GroupSideEffectStep` now do lazy reductions to reduce memory footprint. Breaking change for `group()` semantics.
* Added `GroupStepHelper` with various static methods and classes that are used by both `GroupStep` and `GroupSideEffectStep`.
* Added `BarrierStep` interface with `processAllStarts()` method which process all starts up to yielding the barrier result.
* Fixed a severe threading issue in `TinkerGraphComputer`.
* The location of the jars in HDFS is now `hadoop-gremlin-x.y.z-libs` to ensure multiple TinkerPop versions don't clash.
* `GiraphGraphComputer` will only upload the jars to HDFS if it doesn't already exist (to help speed up startup time).
* `GiraphGraphComputer.workers()` is smart about using threads and machines to load balance TinkerPop workers across cluster.
* `GraphComputer.workers(int)` allows the user to programmatically set the number of workers to spawn.
* Added `GryoSerializer` as the new recommended Spark `Serializer`. Handles `Graph` and `GryoMapper` registries.
* `GryoPool` now makes use of `GryoPool.Builder` for its construction.
* Bumped to Apache Hadoop 2.7.1.
* Bumped to Apache Giraph 1.1.0.
* Bumped to Apache Spark 1.5.1.
* Split Hadoop-Gremlin apart such there is now `hadoop-gremlin`, `spark-gremlin`, and `giraph-gremlin` (and respective `GremlinPlugins`).
* Added `LambdaCollectingBarrierStep` which generalizes `NoOpBarrierStep` and allows for `barrier(normSack)`-type operations.
* Fixed bugs in the Gremlin Server's NIO protocol both on the server and driver side.
* Added `Path.popEquals(Pop,Object)` to check for path equality based on `Pop` (useful for `TraverserRequirement.LABELED_PATH`).
* Added `Operator.assign` to allow setting a direct value.
* `Operator` is now a `BinaryOperator<Object>` with appropriate typecasting for respective number operators.
* Simplified `SackValueStep` so it now supports both `sack(function)` and `sack(function).by()`. Deprecated `sack(function,string)` .
* Added `Parameters` object to allow for the parameters of a step to be retrieved at runtime via a traversal.
* Redesigned (though backwards compatible) `AddEdgeStep`, `AddVertexStep`, and `AddPropertyStep` (and respective `GraphTraversal` API).
* Added `GraphTraversalSource.inject()` so users can spawn a traverser with non-graph objects.
* `GraphStep` can now take a single argument `Collection` which is either elements or element ids (i.e. `g.V([1,2,3])` is supported now).
* Added `LoopsStep` to make the loop counter accessible within `repeat()`, `until()` and `emit()`.
* Gephi Plugin no longer requires manual insert of `store` steps to visualize a traversal.
* Added a `TinkerIoRegistry` that registers a custom serializer for Gryo that will serialize an entire `TinkerGraph` instance.
* Added configuration options to Gephi Plugin for setting the size of nodes visualized.
* Replaced `DedupBijectionStrategy` with the more effective `FilterRankingStrategy`.
* `ComputerAwareSteps` must not only handle step ids, but also step labels.
* Renamed `B_O_P_SE_SL_Traverser` to `B_LP_O_P_SE_SL_Traverser` as it now supports `TraverserRequirement.LABELED_PATH`.
* Added `B_LP_O_S_SE_SL_Traverser` in support of `TraverserRequirement.LABELED_PATH`.
* Added `TraverserRequirement.LABELED_PATH` which only generates path data for steps that are labeled (greatly increases the likelihood of bulking).
* Fixed a bug in `Path` usage that required an API update: `Path.addLabel()` is now `Path.extend(Set<String>)` and `Traverser.addLabels(Set<String>)`.
* Made `Path` iterable, so that it can be ``unfold()``'ed and used by local steps like `min(local)`, `max(local)`, etc.
* `WhereTraversalStep` and `WherePredicateStep` are now the only "special" `Scoping` steps after `MatchStartStep` in `match()`.

==== Bugs

* TINKERPOP-774 order / dedup issues
* TINKERPOP-799 [Proposal] with()-modulator for stream level variable binding.
* TINKERPOP-801 groupCount() fails for vertices (elements?) (using Spark)
* TINKERPOP-811 AddPropertyStepTest fails "all of a sudden"
* TINKERPOP-823 addV() broken for multi-value properties
* TINKERPOP-843 Misspecified HADOOP_GREMLIN_LIBS generates NullPointerException
* TINKERPOP-857 Add GraphComputer.config(key,value)
* TINKERPOP-895 Use "as BinaryOperator" and remove GBinaryOperator
* TINKERPOP-903 Fix empty buffer return upon buffer capacity exceeded
* TINKERPOP-910 In session transaction opened from sessionless request
* TINKERPOP-918 ComputerVerificationStrategy is too restrictive
* TINKERPOP-926 Renamed TinkerGraph public statics to common pattern used for other statics.
* TINKERPOP-948 AbstractGremlinProcessTest.checkMap not asserted in GroupTest
* TINKERPOP-953 Artifact equality is not evaluating properly
* TINKERPOP-955 HashMap$Node not serializable

==== Improvements

* TINKERPOP-297 Ensure Consistent Behavior Over Deleted Elements *(breaking)*
* TINKERPOP-333 Support VertexProperty in PartitionStrategy
* TINKERPOP-391 More fluency in GraphComputer for parameterization.
* TINKERPOP-616 Use Spark 1.3.0 in Hadoop-Gremlin.
* TINKERPOP-624 Passing Detached/Referenced to Graph.vertices/edge()
* TINKERPOP-680 Configurable Channelizer for Gremlin Driver
* TINKERPOP-728 Improve Remote Graph Object Treatment in Console
* TINKERPOP-756 Provide a strict parsing option for GraphMLReader
* TINKERPOP-760 Make loop counter accessible within repeat()
* TINKERPOP-762 Allow mid-traversal V() (and E())
* TINKERPOP-765 Decompose AbstractTransaction for different transactional contexts *(breaking)*
* TINKERPOP-767 Path should play well with "local" steps.
* TINKERPOP-768 MatchStep in OLAP should be smart about current vertex.
* TINKERPOP-769 Make the introduction of the TP3 docs story better.
* TINKERPOP-772 TraverserRequirement.LABELED_PATH
* TINKERPOP-796 Support merge binary operator for Gremlin sacks *(breaking)*
* TINKERPOP-798 [Proposal] Rename mapKeys()/mapValues() to select(keys) and select(values).
* TINKERPOP-802 Provide sack(object) so that the sack can be directly set.
* TINKERPOP-803 A better solution to g.V(someCollection.toArray())
* TINKERPOP-805 Enforce AutoCloseable Semantics on Transaction *(breaking)*
* TINKERPOP-821 Improve testing around TraversalHelper around recursive methods
* TINKERPOP-825 [Proposal] SetBulkStep (sideEffectStep)
* TINKERPOP-826 OneToManyBarrierStrategy
* TINKERPOP-827 Add a console session to the PageRank section of the docs.
* TINKERPOP-829 TinkerGraphComputer should support the user specified thread/worker count.
* TINKERPOP-835 Shade Jackson Dependencies *(breaking)*
* TINKERPOP-836 Support Hadoop2 in place of Hadoop1
* TINKERPOP-850 Reduce Graph.addVertex overload ambiguity *(breaking)*
* TINKERPOP-851 GroupCountStep needs a by() for the count.
* TINKERPOP-861 Solve "The Number Problem" for Operator (and follow on operators)
* TINKERPOP-863 [Proposal] Turn off bulking -- or is there something more general? (hope not).
* TINKERPOP-866 GroupStep and Traversal-Based Reductions *(breaking)*
* TINKERPOP-868 Allow Spark Gremlin Computer to Reuse Spark Contexts
* TINKERPOP-874 Rename Gremlin-Spark properties using gremlin.spark prefix. *(breaking)*
* TINKERPOP-876 Rename VendorOptimizationStrategy XXXOptimizationStrategy *(breaking)*
* TINKERPOP-879 Remove deprecated promoteBindings from GremlinExecutor *(breaking)*
* TINKERPOP-885 Change Transaction.onReadWrite() to be a ThreadLocal setting *(breaking)*
* TINKERPOP-888 GraphTraversal.property overloads *(breaking)*
* TINKERPOP-896 Simplify the {{withSack}} methods of {{GraphTraversalSource}}. *(breaking)*
* TINKERPOP-897 Remove deprecated GSupplier, GFunction, GConsumer, etc. methods. *(breaking)*
* TINKERPOP-898 Rename ConjuctionP and ConjuctionStep to ConnectiveP and ConnectiveStep *(breaking)*
* TINKERPOP-899 Bump to the latest version of Neo4j.
* TINKERPOP-900 Provide by(object) which compiles to by(constant(object))
* TINKERPOP-901 Option for use of Netty epoll on Linux to reduce GC pressure
* TINKERPOP-904 BulkLoaderVertexProgram optimizations
* TINKERPOP-905 Harden time oriented tests in ResultQueueTest
* TINKERPOP-907 getters for RepeatStep.untilTraversal and RepeatStep.emitTraversal
* TINKERPOP-908 Use line breaks in documentation
* TINKERPOP-909 Improve steps that handle numeric data
* TINKERPOP-911 Allow setting Thread Specific Spark JobGroup/Custom Properties based on hadoop conf
* TINKERPOP-913 Rename Gremlin Server arguments rebinding to alias
* TINKERPOP-914 DriverRemoteAcceptor in Gremlin Console supports aliases
* TINKERPOP-917 Add HadoopGraph.open(String)
* TINKERPOP-922 Add a book for Developer Documentation
* TINKERPOP-923 Add a book for Tutorials
* TINKERPOP-925 Use persisted SparkContext to persist an RDD across Spark jobs.
* TINKERPOP-931 Make it possible to extend the core OpProcessor implementations
* TINKERPOP-933 Improve release process to get files named properly
* TINKERPOP-935 Add missing "close" operation to the session opProcessor docs

== TinkerPop 3.0.0 (A Gremlin Rāga in 7/16 Time)

image::https://raw.githubusercontent.com/apache/tinkerpop/master/docs/static/images/gremlin-hindu.png[width=225]

[[release-3-0-2-incubating]]
=== TinkerPop 3.0.2 (Release Date: October 19, 2015)

* Cleaned up `ext/` directory when plugin installation fails for `gremlin-server` and `gremlin-console`.
* Fixed issues in `gremlin-server` when configured for HTTP basic authentication.
* Made `BulkLoaderVertexProgram` work for any persistent TP3-supporting graph (input and output).
* `TreeSideEffectStep` now implements `PathProcessor` which fixed a `ComputerVerificationStrategy` issue.
* Added a shell script that verifies source and binary distributions.
* Fixed a bulk related bug in `GroupStep` when used on `GraphComputer` (OLAP).
* Gremlin Server binary distribution now packages `tinkergraph-gremlin` and `gremlin-groovy` as plugins to be consistent with Gremlin Console's packaging.
* The `RepeatStep` clauses (`until()`,`emit()`,`repeat()`) can only be set at most one time in order to prevent user confusion.
* Fixed a `clone()` bug in `RepeatStep`, `TreeStep`, `GroupCountStep`, `GroupStep`, and `TraversalRing`.
* Fixed a thread context bug in `TinkerGraphComputer`.
* Fixed issues with the `gremlin-driver` related to hanging connections in certain conditions.
* TinkerGraph now has an option for persistence where the data is saved on `close()` and, if present, loaded on `open()`.
* Added an overload for `GremlinExecutor.eval()` that takes a `Lifecycle` object to override some default settings from `GremlinExecutor.Builder`.
* Improved session closing for transactional graphs during shutdown of Gremlin Server.
* Fixed id parameter used in tests for `GroovyStoreTest` and `GroovyRepeatTest` to not be treated as an embedded string.
* `GraphStep` will convert any `Vertex` or `Edge` ids to their id `Object` prior to submission to `GraphComputer` (OLAP).

==== Bugs

* TINKERPOP-814 ConnectionPool can fill with dead Connections
* TINKERPOP-816 Gryo deserialization of error response with null message causes NPE and protocol desync
* TINKERPOP-817 Gryo serialization of large responses fails and causes protocol desync
* TINKERPOP-840 TreeTest Is not being ignored via ComputerVerificationStrategy
* TINKERPOP-849 gremlin-server doesn't close sessions on 'close' opcode
* TINKERPOP-855 sasl authentication type error due to Json format
* TINKERPOP-865 Errors with HTTP REST basic auth
* TINKERPOP-867 TinkerGraphProvider does not initialize temp dir
* TINKERPOP-870 Rebound client requires a connection to occur on the underlying client.
* TINKERPOP-877 Driver hangs if SSL enabled on server but not on client

==== Improvements

* TINKERPOP-828 TinkerGraph can supportPersistence(), should we allow it.
* TINKERPOP-830 process-docs.sh introduces extra white space dependent on console width
* TINKERPOP-839 Docs should have a ${version.number} under the logo.
* TINKERPOP-852 A shell script that validates the distribution artifacts at release time
* TINKERPOP-853 TinkerPop Logo in JavaDoc index.html
* TINKERPOP-858 Cleanup after failed :install

[[release-3-0-1-incubating]]
=== TinkerPop 3.0.1 (Release Date: September 2, 2015)

* `Compare` now uses `BigDecimal` internally to ensure that precision is not lost on standard number comparisons.
* Renamed `ComputerVerificationStrategy` to `VerificationStrategy` so all the verification strategies can use it.
* Added `StandardVerificationStrategy` that throws exceptions for illegal traversal patterns on the standard engine (which extends to `GraphComputer`).
* Added `GraphFeatures.supportsConcurrentAccess()` to allows `Graph` implementations to signify if multiple instances can access the same data.
* Clarified semantics of `Transaction.close()` in unit tests - now refers only to closing the current transaction in the current thread.
* `Neo4jGraph` no longer uses `OptOut` on `TransactionTest.shouldRollbackOnCloseWhenConfigured` (formerly `shouldRollbackOnShutdownWhenConfigured`)
* Gremlin Server initialization scripts can now return a `Map` of values that will become global bindings for the server.
* Introduced the `--dryRun` option to the document generation process which ignores actual script execution in the Gremlin Console.
* Fixed bug in `EventStrategy` around property changed events when calling `property` without cardinality or meta-property values.
* Improved support for the `Accept` header for REST-based requests in Gremlin Server.
* `GraphFactory` now allows specification of the class to use to instantiate the `Graph` through the `GraphFactoryClass` annotation.
* Added `wrapAdjacencyList` and `unwrapAdjacencyList` options to `GraphSONWriter` and `GraphSONReader` respectively, thus allowing valid JSON to be written/read if the user desires.
* Added Gremlin Server/Driver authentication support via SASL.
* Added Basic HTTP authentication support for REST in Gremlin Server.
* Added Gremlin Server plugin to help with "credential graph" management (used in conjunction with authentication features of Gremlin Server).
* Added "secure" Gremlin Server/Driver example configuration files.
* Adjusted configuration for javadoc generation to eliminate error messages.
* Removed "reserved" graph concept names from tests (e.g. "label", "edge", "value") to support the convention of avoiding these strings for property names.
* Introduced `GraphProvider.Descriptor` which annotates a `GraphProvider` implementation to describe what `GraphComputer` implementation will be used.
* Modified `OptOut` to include a `computers` attribute which allows the `Graph` to opt-out of computer-based tests for specific computation engines.
* Added a `SandboxExtension` that can be plugged into `TypeCheckedCustomizerProvider` and `CompileStaticCustomizerProvider` to control classes and methods that can be used in the `GremlinGroovyScriptEngine`.
* Added a number of new `ImportCustomizerProvider` implementations such as, `TimedInterruptCustomizerProvider`, `TypeCheckedCustomizerProvider` and others.
* Refactored `GremlinGroovyScriptEngine` to make more general use of `ImportCustomizerProvider` implementations.
* Removed `SecurityCustomizerProvider` class and the "sandbox" configuration on the `ScriptEngines` class - this was an experimental feature and not meant for public use.
* Removed dependency on `groovy-sandbox` from the `gremlin-groovy` module.

==== Bugs

* TINKERPOP-770 Exception while AddPropertyStep tries to detach vertex property
* TINKERPOP-780 Use of fold() in repeat()
* TINKERPOP-782 map(Traversal) should declare requirements of child
* TINKERPOP-785 Gremlin Server Not Properly Reporting Port Conflict
* TINKERPOP-792 select at start of match traversal on Map can fail
* TINKERPOP-794 IncidentToAdjecentStrategy malfunction
* TINKERPOP-804 Failed installing neo4j-gremlin extension on Windows 7
* TINKERPOP-822 Neo4j GraphStep with element arguments ignores has  *(breaking)*

==== Improvements

* TINKERPOP-576 Gremlin Server Authentication
* TINKERPOP-582 Remove Groovy Sandbox Dependency
* TINKERPOP-610 General graph concept names in test schema
* TINKERPOP-656 IoRegistry Chaining
* TINKERPOP-690 Be able to OPT_OUT for Standard, but not Computer *(breaking)*
* TINKERPOP-699 GraphSON writeGraph not producing valid json object
* TINKERPOP-750 Compare should not have special case for Number
* TINKERPOP-752 Make Gremlin Server Better Respect ACCEPT
* TINKERPOP-764 Unify semantics of Transaction.close() in tests and documentation *(breaking)*
* TINKERPOP-771 IoRegistry Instantiation With GryoPool
* TINKERPOP-778 Support GraphFactory location via annotation.
* TINKERPOP-791 Document rules for committers
* TINKERPOP-797 order() seems to only like List? *(breaking)*
* TINKERPOP-808 TraversalComparator.comparator needs a getter

=== TinkerPop 3.0.0 (Release Date: July 9, 2015)

* Modified the `GremlinExecutor` to catch `Throwable` as opposed to `Exception` so as to properly handle `Error` based exceptions.
* Modified the `GremlinGroovyScriptEngine` compilation configuration to prevent inappropriate script evaluation timeouts on standalone functions.
* Added a custom configuration for "timed interrupt" in the `ScriptEngines` instantiation of the `GremlinGroovyScriptEngine`.
* Added `mapKeys()` (`MapKeyStep`) and `mapValues()` (`MapValueStep`) to get the keys and values of a map, respectively.
* `select()` no longer supports empty arguments. The user must specify the keys they are selecting.
* `MatchStep` and `match()` no longer have a "start label" parameter -- it is computed if the incoming traverser does not have requisite labels.
* Turned transactional testing back on in Gremlin Server using Neo4j.
* Renamed `Transaction.create()` to `Transaction.createThreadedTx()`.
* Added `TraversalParent.removeGlobalChild()` and `TraversalParent.removeLocalChild()`.
* Added a `clear` option to the Gephi Plugin to empty the Gephi workspace.
* Refactored `ResultSet` and related classes to stop polling for results.
* `AbstractStep` now guarantees that bulk-less and null-valued traversers are never propagated.
* Added `dedup(string...)` which allows for the deduplication of a stream based on unique scope values.
* Fixed multiple bugs in the Gephi Plugin related to refactoring of traversal side-effects.
* Split `WhereStep` into `WherePredicateStep` and `WhereTraversalStep` to simplify internals.
* Prevent the driver from attempting to reconnect on a dead host if the `Cluster.close()` method has been called.
* Renamed the "deactivate" option on `:plugin` command to "unuse" to be symmetric with the "use" option.
* Added `Traversal.toStream()` to turn the `Traversal<S,E>` into a `Stream<E>`.
* Added `Scoping.Variable` enum of `START` and `END` which allows the `Scoping` step to specify where its bindings are.
* `ComputerVerificationStrategy` is smart about not allowing `WhereXXXStep` with a start-variable to run in OLAP as it selects the value from the path.
* Rewrote `MatchStep` where it now works on `GraphComputer`, solves more patterns, provides plugable execution plans, supports nested AND/OR, `not()`-patterns, etc.
* Renamed `Graphs` in Gremlin Server to `GraphManager`.
* Fixed bug in Gremlin Driver where client-side serialization errors would not bubble up properly.
* Fixed problem in Gremlin Server to ensure that a final `SUCCESS` or `NO_CONTENT` message assured that the transaction was successful in sessionless requests.
* Arrow keys for cycling through command history now work in Gremlin Console when being used on Windows.
* Added `NotStep` and `not(traversal)` for not'ing a traversal (integrates like `ConjunctionStep`).
* Removed `TraversalP`. Traversals and `P`-predicates are completely separate concepts.
* `has(key,traversal)` is now an alias for `filter(__.values(key).traversal)` using `TraversalFilterStep`.
* Simplified `SubgraphStrategy` by using `TraversalFilterStep` instead of the more complex `WhereStep`.
* Added `TraversalMapStep`, `TraversalFlatMapStep`, `TraversalFilterStep`, and `TraversalSideEffectStep` which all leverage an internal traversal.
* Added `Path.get(pop,label)` as default helpers in `Path`.
* Added `Pop.first`, `Pop.last`, and `Pop.all` as enums for getting single items from a collection or a list of said items.
* Changed `GremlinServer.start()` to return a `CompletableFuture` that contains the constructed `ServerGremlinExecutor`.
* Restructured `IoTest` breaking it up into smaller and more logically grouped test cases.
* Gremlin Server `Settings` now has sensible defaults thus allowing the server to be started with no additional configuration.
* Fixed garbled characters in Gremlin Console that notably showed up in `:help`
* Replaced dependency on `groovy-all` with individual Groovy dependencies as needed.
* Bumped `org.gperfutils:gbench` to the `0.4.3` and a version explicitly compatible with Groovy 2.4.x.
* Renamed `KeyStep` to `PropertyKeyStep` to be consistent with `PropertyValueStep`.
* Added `Gremlin-Lib-Paths` to modify paths in plugin `lib` directory.
* Modified the capabilities of `Gremlin-Plugin-Paths` to delete paths that have no value on the right-hand-side of the equals sign.
* The REST API in Gremlin Server now requires parameters to be defined with a "bindings." prefix.
* Modified the REST API in Gremlin Server to accept rebindings.
* Added `rebindings` optional argument to sessionless requests to allow global bindings to be rebound as needed.
* Added `LazyBarrierStrategy` which "stalls" a traversal of a particular form in order to gain a bulking optimization.
* `CollectingBarrierStep` supports `maxBarrierSize` for "lazy barrier," memory conservation.
* `Scoping` now has `getScopeKeys()` to get the keys desired by the scoping step.
* Refactored SSL support in the Gremlin Server/Driver.
* Factored out `ServerGremlinExecutor` which contains the core elements of server-side script execution in Gremlin Server.
* Bumped to netty 4.0.28.Final.
* Refactored the `Mutating` interface and introduce `CallbackRegistry` interface around `EventStrategy`.
* Changed `onReadWrite` and `onClose` of `AbstractTransaction` to be synchronized.
* Added `LabelP` to support index lookups and `has()` filtering on `Neo4jGraph` multi-label vertices.
* `AddEdgeStep` is now a `Scoping` step.
* Added a fully defined set of `Graph.Feature` implementations to `EmptyGraph`.
* Dropped dependency on `org.json:json` - used existing Jackson dependency.
* Added back neo4j-gremlin as the licensing of the Neo4j API is now Apache2.
* Added `willAllowId` method to features related to vertices, edges and vertex properties to test if an identifier can be use when `supportsUserSuppliedIds` is `true`.
* Fixed a bug in `GraphTraversal.choose(predicate,trueTraversal,falseTraversal)`.
* Removed `MapTraversal`, `MapTraverserTraversal`, `FilterTraversal`, and `FilterTraverserTraversal` as these are simply `__.map(function)` and `__.filter(predicate)`.
* Include `hadoop-gremlin` Hadoop configuration sample files in Gremlin Console distribution.
* Iteration of results in Gremlin Server occur in the same thread as evaluation and prior to transaction close.
* TinkerGraphComputer now supports every `ResultGraph`/`Persist` combination.
* `GraphComputerTest` extended with validation of the semantics of all `ResultGraph`/`Persist` combinations.
* GiraphGraphComputer no longer requires an extra iteration and MapReduce job to derive the full `Memory` result.
* SparkGraphComputer now supports `InputRDD` and `OutputRDD` to allow vendors/users to use a `SparkContext` to read/write the graph adjacency list.
* Added `Scoping.getScopeValue()` method so all "selecting" steps use the same pattern for map, path, and sideEffect data retrieval.

=== TinkerPop 3.0.0.M9 (Release Date: May 26, 2015)

* Removed `GraphComputer.isolation()` as all implementations use standard BSP.
* Added a Gremlin Server `LifeCycleHook` to ensure that certain scripts execute once at startup and once at shutdown.
* `has(key)` and `hasNot(key)` are now aliases for `where(values(key))` and `where(not(values(key)))`, respectively.
* TinkerGraph classes are now final to restrict user and vendor extension.
* Added `TraversalStrategy.VendorOptimization` to ensure that all TinkerPop optimizations execute first on the known TinkerPop steps.
* Added `TailGlobalStep` and `TailLocalStep` (`tail()`) which gets objects from the end of the traversal stream.
* `AndStep` and `OrStep` are now simply markers where `WhereStep(a.and(b).and(c)...and(z))` is the compilation.
* Moved `Compare`, `Contains`, `Order`, `Operator`, and `P` to `process/traversal` from `structure/` as they are process-based objects.
* `HasContainer` now uses `P` predicate as helper methods and tests are more thorough on `P`.
* Changed Gremlin Server integration/performance tests to be runnable from within the `gremlin-server` directory or from the project root.
* Moved the string methods of `TraversalHelper` to `StringFactory`.
* Renamed JSON-related serializers for Gremlin Server to be more consistent with GraphSON naming.
* Removed `HasTraversalStep` in favor of new `P.traversal` model with `HasStep`.
* Fixed bug in `WsGremlinTextRequestDecoder` where custom serializers from graphs were not being used.
* Added `AndP` which allows for the `and()`-ing of `P` predicates.
* `Order.opposite()` is now `reversed()` as that is a `Comparator` interface method with the same semantics.
* `Compare/Contains/P.opposite()` are now `negate()` as that is a `BiPredicate` interface method with the same semantics.
* `has(traversal)` is replaced by `where(traversal)` and `has(key,traversal)`. `HasXXX` is always with respects to an element property.
* Added `TraversalScriptHelper` with static methods for dynamically creating a `Traversal` from a JSR 223 `ScriptEngine`.
* Changed `SubgraphStrategy` to take `Traversal` rather than `Predicate` for filtering.
* Improved `SubgraphStrategy` to only modify the `Traversal` if filtering was required.
* Improved logging of errors in the `HttpGremlinEndpointHandler` to include a stracktrace if one was present.
* Moved `AbstractGremlinSuite.GraphProviderClass` to `org.apache.tinkerpop.gremlin.GraphProviderClass`.
* Simplified the Gremlin-Groovy test suite where there is now no distinction between `STANDARD` and `COMPUTER` tests.
* `VertexProgram` and `MapReduce` now add a `Graph` parameter to `loadState(Graph, Configuration)`.
* Added `ScopingStrategy` which auto-scopes `select()` and `where()` so the language looks clean.
* Added `Scoping` as a marker interface to state that a step desires a particular `Scope`.
* `SelectStep`, `SelectOneStep`, and `WhereStep` support both `Scope.local` and `Scope.global` for `Map<String,Object>` or `Path` analysis, respectively.
* Fixed a bug in the `TraversalStrategies` sort algorithm.
* Removed numerous unused static utility methods in `TraversalHelper`.
* TinkerGraph process suite tests are now running with and without strategies in place.
* Added `IncidentToAdjacentStrategy` which rewrites `outE().inV()`, `inE().outV()` and `bothE().otherV()` to `out()`, `in()` and `both()` respectively.
* Renamed `ComparatorHolderRemovalStrategy` to `OrderGlobalRemovalStrategy` as it now only applies to `OrderGlobalStep`.
* Anonymous traversal no longer have `EmptyGraph` as their graph, but instead use `Optional<Graph>.isPresent() == false`.
* Added `Traversal.Admin.setGraph(Graph)` as strategies that need reference to the graph, need it across all nested traversals.
* `AbstractLambdaTraversal` is now smart about `TraversalParent` and `TraversalStrategies`.
* Fixed bug in `GraphML` reader that was not allowing `<edge>` elements to come before `<node>` elements as allowable by the GraphML specification.
* Added `VertexFeature.getCardinality`.
* Added `AdjacentToIncidentStrategy` which rewrites `out().count()` to `outE().count()` (and similar such patterns).
* `GryoPool` now takes a `Configuration` object which allows setting the size of the pool and the `IoRegistry` instance.
* Added `PersistResultGraphAware` interface which is used by `OutputFormats` to specify persistence possibilities for a Hadoop `GraphComputer`.
* `ElementIdStrategy` now allows the identifier property to be set directly (and not only by specifying `T.id`).
* Added sample configuration files for registering a `TraversalStrategy` in Gremlin Server.
* Added response status code for `NO_CONTENT` to represent output for a successful script execution without a result (e.g. an empty `Iterator`).
* Removed the notion of a "terminator" message from the Gremlin Server protocol - new response status code for `PARTIAL_CONTENT`.
* `Path` and `Step` labels are ordered by the order in which the respective `addLabel()` calls were made.
* A `Step` now has a `Set<String>` of labels. Updated `as()` to take a var args of labels.
* Dropped `BatchGraph` from the code base - it will be replaced by bulk loader functionality over OLAP.
* `TraversalSideEffects` now implements `Optional` semantics. Less code as Java8 provides the helper methods.
* `TraversalScriptSupplier` now takes an `Object` var args for setting `ScriptEngine` bindings if needed.
* `Compare` is now more lenient on `Number`-types.
* Removed `Compare.inside` and `Compare.outside` as they are not primitive comparators and should be composed from primitives.
* Introduced `P` (predicate) for cleaner looking `is()`, `has()`, and `where()` calls -- e.g. `has('age',eq(32))`.
* `GraphTraversalSource` is now the location for `withXXX()` operations. No longer do they exist at `GraphTraversal`.
* All `Traverser` objects now extend from `AbstractTraverser` or a child that ultimately extends from `AbstractTraverser`.
* OLTP `select()` now returns a list for traversals with duplicate labels (as this was a unintended side-effect of `SparsePath`).
* Removed the `SparsePath` optimization as it led to numerous corner-case inconsistencies.
* `VertexWritable` serializes and deserializes the `StarGraph` object -- no more intermediate `DetachedXXX` objects.
* Gremlin Server better supports the settings for the high and low watermark that will slow writes to clients that are lagging.
* Added `GraphReader.readObject()` and `GraphWriter.writeObject` abstractions for those implementations that can support them.
* Altered `GraphWriter.writeVertices()` method to take an `Iterator` of vertices rather than a `Traversal`.
* GraphSON format for output from `GraphWriter.writeVertex`, `GraphWriter.writeVertices`, and `GraphWriter.writeGraph` have all changed now that they use `StarGraph` serialization.
* Gryo format for output from `GraphWriter.writeVertex`, `GraphWriter.writeVertices`, and `GraphWriter.writeGraph` have all changed now that they use `StarGraph` serialization.
* Added read and write methods to `GraphReader` and `GraphWriter` for `Property` and `VertexProperty`.
* Reduced object creation in GraphSON during serialization.
* Moved `T` tokens to the `structure/` package as its more general than `process/`.
* `Attachable.attach()` now takes a `Method` to determine whether to attach via `GET`, `CREATE`, or `GET_OR_CREATE`.
* Decreased size of Gremlin Server `RequestMessage` and `ResponseMessage` serialization payloads and reduced object creation.
* `Graph.empty()` no longer required with the introduction of `ShellGraph` which is a placeholder for a graph class and computer.
* `VertexProperty.Cardinality` default is now vendor chosen. If the vendor has not preference, they should use `Cardinality.single`.
* `Messenger.receiveMessages()` no longer takes a `MessageScope` and thus, consistent behavior between message-passing and message-pulling systems.
* Changed the `gremlin.tests` environment variable for test filtering to the more standard convention of `GREMLIN_TESTS` and made it work for all test suites.
* Removed `back()`-step as `select()`-step provides the same behavior with more intelligent optimizations and `by()`-modulation.
* Removed `Graph.Helper` method annotation and related infrastructure in tests.
* Modified header of Gryo to be 16 bytes instead of 32 (and removed the version stamp).
* Removed the concept of handling version in Gryo via the builder as it wasn't really accomplishing the capability of ensuring backward compatibility.
* Moved `Exceptions.propertyRemovalNotSupported` from `Element` to `Property` for consistency.
* Provided a method for Gremlin Server to bind `TraversalSource` objects for use in scripts.
* Modified the reference implementation for dealing with "custom" identifier serialization in GraphSON - See `IoTest.CustomId` for the example.
* Modified `g.vertices/edges` and related methods and tests to support non-type specific querying (e.g. `g.V(1)` and `g.V(1L)` should both return the same result now).
* `TinkerGraph` supports an `IdManager` which helps enforce identifier types and improve flexibility in terms of how it will respond to queries around identifiers.
* `DetachedXXX` now uses the standard `structure/` exceptions for unsupported operations.
* Added private constructors to all `Exceptions` inner classes in the respective `structure/` interfaces.
* Re-introduced `ReferenceXXX` to ensure a smaller data footprint in OLAP situation (`DetachedXXX` uses too much data).
* `Attachable` now has a set of static exception messages in an `Exceptions` inner class.
* Added `StarGraph` which is a heap efficient representation of a vertex and its incident edges (useful for `GraphComputer` implementations).
* `TraverserSet` uses a `FastNoSuchElementException` on `remove()` for increased performance.
* Add `Profiling` interface to enable vendors to receive a `Step's MutableMetrics`.

=== TinkerPop 3.0.0.M8 (Release Date: April 6, 2015)

* Removed Neo4j-Gremlin from this distribution due to GPL licensing. Working with Neo4j team to reintroduce by M9.
* Altered structure of plugin directories for Gremlin Server and Gremlin Console to allow for the full `lib` directory with all dependencies and the lighter `plugin` directory which contains filtered dependencies given the path.
* Improved `OptOut` to allow for exclusion of a group of tests by specifying a base test class.
* `GraphComputerTest` is now Java8 specific and much easier to extend with new test cases.
* Merged the `gremlin-algorithm` module into `gremlin-test`.
* Removed `LambdaVertexProgram` and `LambdaMapReduce` as it will be one less thing to maintain.
* Gremlin Console accepts a `max-iteration` configuration via the standard `:set` command to limit result iteration.
* `Vertex.property()` default behavior is now `Cardinality.single`.
* Added `ElementIdStrategy` as a `TraversalStrategy`.
* Introduce `AbstractTransaction` to simplify implementation of standard transactional features for vendors.
* Added `EventStrategy` to generate `Graph` modification events to listeners.
* Added test to enforce return of an empty `Property` on `VertexProperty.property(k)` if no meta properties exist.
* Added methods to registered transaction completion listeners on `Transaction` and provided a default implementation.
* Fixed bug in Neo4j where return of an empty meta property was returning a `NullPointerException`.
* Refactored step API -- the TinkerPop3 steps are the foundation for any domain specific language (including graph).
* `MapReduce` now has `workerStart(Stage)` and `workerEnd(Stage)` methods with analagous semantics to `VertexProgram`.
* Hadoop-Gremlin `ObjectWritable` now leverages Kryo for data serialization.
* `GiraphGraphComputer` supports arbitrary objects as the vertex id -- previously, only long ids were supported.
* Added `VertexProgramPool` to support thread safe pooling of vertex programs for graph computers that provide threaded workers.
* Added `GryoPool` to support thread safe pooling of Gryo readers and writers.
* Added `TraversalSource` which contextualizes a traversal to a graph, DSL, execution engine, and runtime strategies.
* Added `AddVertexStep` (`addV`), `AddPropertyStep` (`property`), and changed `AddEdgeStep` to a map-step instead of a sideEffect-step.
* Added `compile` method to `GremlinExecutor` and related classes.
* Fixed bug in Gremlin Server that was generating extra response messages on script evaluation errors.
* Changed the `Memory` API to not return the mutated value on `or`, `and`, `incr` as it is too difficult to implement faithfully in a distributed system.
* Added `SparkGraphComputer` to Hadoop-Gremlin which uses Apache Spark as the underlying computing engine.
* Renamed "Gremlin Kryo" to "Gryo".
* Refactored `TinkerWorkerPool` to use `ExecutorService` so as to reuse threads when executing graph computer functions.
* Removed `Reducing.Reducer` and `ReducingStrategy`. Previous `Reducing` classes are now `MapReducer` classes.
* Refactored the "process" test suite to allow for better test configuration with respect to different `TraversalEngine` implementations.
* Added `hasNot(traversal)` which is a faster way of doing `has(traversal.count().is(0L))`.
* `TraversalStrategy.apply(traversal)` is the new method signature as the `TraversalEngine` can be retrieved from the `Traversal`.
* `TraversalEngine` is now an interface and provided to the traversal by the graph. `Graph` methods added to set the desired traversal engine to use.
* Added `count(local)`, `sum(local)`, `max(local)`, `min(local)`, `mean(local)`, `dedup(local)`, `sample(local)` and `range(local)` for operating on the local object (e.g. collection, map, etc.).
* `TraversalComparator` exists which allows for `order().by(outE().count(),decr)`.
* Added Apache Rat plugin to detect the proper inclusion of license headers in files.
* A `Traversal` now respects thread interruption during iteration, throwing a `TraversalInterruptionException` if it encounters interruption on the current thread.
* Apache refactoring: `com.tinkerpop` -> `org.apache.tinkerpop`.
* `Traversal` is now `Serializable` and with most queries no longer needing lambdas, Gremlin-Java works over the wire.
* Added `VertexProperty.Cardinality` with `list`, `set`, and `single`. No more `Vertex.singleProperty()` method.
* Added `RangeByIsCountStrategy` that adds a `RangeStep` in front of `.count().is(<predicate>, <value>)` to minimize the amount of fetched elements.
* Added `CoalesceStep` / `coalesce()` that emits the first traversal which emits at least one element.
* Added more syntactic sugar tricks to the Gremlin sugar plugin -- `&`, `|`, `select from`, `gt`, etc.
* `Traversal.Admin` is consistent internal to steps, traversals, strategies, etc. For the user, `Traversal` is all they see.
* `TraversalHolder` is now called `TraversalParent` with the child/parent terminology used throughout.
* Added `GroovyEnvironmentPerformanceSuite`.
* Provided more robust shutdown capabilities for the thread pools used in `GremlinExecutor`.
* A massive `process/` package reorganization -- class names are still the same, just in new packages.
* Bumped `neo4j-graph` to Neo4j 2.1.6.
* Bumped to Groovy 2.4.1.
* Added a new "performance" test suite for Gremlin Process.
* Steps now only operate with traversals -- no more lambdas. Lambda-> `Traversal` conversion utilities added.
* `SideEffectStep` always requires a `Consumer`. Steps that were consumer-less simply extends `AbstractStep`.
* Simplified the `Neo4jGraph` implementation by now allowing `cypher()` mid-traversal. Only available via `g.cypher()`.
* Moved `clock()` out of the Utility plugin. It is now available to both Groovy and Java.
* Changed the `OptOut` annotation to allow for ignoring an entire test case using a wildcard.
* Added `AndStep` and `OrStep` filters to support arbitrary conjunction of traversals.
* `__` is now a class with static `GraphTraversal` methods and thus `repeat(out())` is possible.
* Added `IsStep` / `.is()` that supports filtering scalar values.
* `Neo4jGraph` and `TinkerGraph` no longer create new `Feature` instances on each feature check.
* Added `Compare.inside` and `Compare.outside` for testing ranges. Removed `between()` as now its `has('age',inside,[10,30])`.
* `GraphTraversal.has()` no longer requires the element type to be cast in the traversal definition.
* Fixed a `ConcurrentModificationException` bug in TinkerGraph that occurred when doing full vertex/edge scans and removing elements along the way.
* Added `Scope.local` and `Scope.global` in support of `OrderLocalStep` and `OrderGlobalStep` via `order(scope)`.
* Added `Order.keyIncr`, `Order.keyDecr`, `Order.valueIncr`, and `Order.valueDecr` in support of `Map` sorting.
* Added `Order.shuffle` and removed `shuffle()` in favor of `order().by(shuffle)`.
* Changed `Order implements Comparator<Comparable>` to `Order implements Comparator<Object>` as its now generalized to multiple types of objects.
* The `maxContentLength` setting in Gremlin Server is now respected by the HTTP/REST Gremlin endpoint.
* Fixed resource leak in the HTTP/REST Gremlin endpoint of Gremlin Server.
* Refactored Gremlin Server `start` and `stop` functions to return `CompletableFuture`.
* HTTP REST error response JSON objects from Gremlin Server should no longer have issues with control characters, line feeds, etc.
* Added `MeanStep`, `mean()`, and `MeanNumber` for calculating number averages in a traversal.
* Greatly simplified all the traversal `MapReduce` implementations due to the introduction of `VertexTraversalSideEffects`.
* Added `VertexTraversalSideEffects` as a cheap, static way to get a sideEffect-view of a vertex in OLAP.
* Added `TraversalHelper.isLocalStarGraph()` which determines if a traversal is contained within the local star graph.
* Added `TraversalVerificationStrategy` to verify if the traversal can be executed on respective engine.
* Refactored `GraphTraversal.cap()` to `GraphTraversal.cap(String...)` to support multi-sideEffect grabs.
* Added GraphSON serialization for `Path`.
* Added `Traversal.Admin.getTraverserRequirements()` and removed `TraversalHelper.getTraverserRequirements(Traversal)`.
* `Traversal.equals()` is no longer computed by determining if the objects returned are equal.
* Altered messaging in Gremlin Console when using a remote that is not yet activated.
* Fixed potential for deadlock in Gremlin Driver when waiting for results from the server.
* Added the `useMapperFromGraph` serializer option to the Gremlin Server configuration file to allow auto-registration of serialization classes.
* Refactored Netty pipeline structure to not have a second "Gremlin" executor group and instead used a standard `ExecutorService`.
* Refactored the `GremlinExecutor` to take an optional transformation function so as to allow manipulation of results from `eval` in the same thread of execution.
* Fixed issue with the `HttpGremlinEndpointHandler` where requests were getting blocked when `keep-alive` was on.
* Added `MinStep` and `MaxStep` with respective `min()` and `max()`.
* `CountStep` and `SumStep` now extend `ReducingBarrierStep` and no longer are sideEffect steps.
* `SideEffectCapStep` now extends `SupplyingBarrier` and is much simpler than before.
* Added `SupplyingBarrier` which simply drains the traversal and emits the value of a provided supplier.
* Added `TraversalLambda` which implements function, predicate, and consumer over a provided traversal.
* Any non-core `Step` that takes a function or predicate can now take a traversal which maps to `traversal.next()` (function) and `traversal.hasNext()` (predicate).
* `CollectingBarrierStep` is no longer abstract and added `GraphTraversal.barrier()` which is analogous to `fold().unfold()`, though cheaper.
* Added `TraversalOptionHolder` for branching steps to index works with corresponding `GraphTraversal.option()`.
* `BranchStep` is now a proper generalization of `UnionStep` and `ChooseStep`.
* `SubgraphStep` has changed in support of in-traversal filtering and removing the need for path-based traversers.
* Added `HasTraversalStep` which takes an anonymous traversal to determine whether or not to filter the current object.
* Added `Traversal.Admin.getStartStep()` and `Traversal.Admin.getEndStep()`. Removed `TraversalHelper.getStart()` and `TraversalHelper.getEnd()`.
* Refactored `profile()` to use injected steps. `ProfileStep` can now be used without any special JVM command line parameters.
* Added `ReducingBarrierStep` which acts like `CollectingBarrierStep` but operates on a seed with a bi-function.
* Added a preprocessor for AsciiDocs. Documentation code examples are executed and the results are dynamically inserted into the doc file.
* `LocalStep` traversal is treated as a branch, not an isolated traversal. Moreover, moved `LocalStep` to `branch/`.
* Traversal strategies are now applied when the `TraversalVertexProgram` state is loaded, not when submitted. Less error prone as it guarantees strategy application.
* Reworked `TraversalHolder` where there are "local traversals" and "global traversals". Local traversals are not subject to OLAP message passing.
* Fixed a bug in `DedupStep` that made itself apparent in `DedupOptimizerStrategy`.
* Added `RepeatStep.RepeatEndStep` in order to reduce the complexity of the code on OLAP when the predicates are not at the start of `RepeatStep`.

=== TinkerPop 3.0.0.M7 (Release Date: January 19, 2015)

* Added `SideEffectRegistrar` interface and `SideEffectRegistrationStrategy` for allowing steps to register sideEffects at strategy application time.
* Renamed `Traverser.Admin.setFuture()` and `Traverser.Admin.getFuture()` to `setStepId()` and `getStepId()`, respectively.
* Added `TraversalMatrix` for random access to steps in a traversal by their step id. Used by `TraversalVertexProgram`.
* Added unique identifies to `Step` that are not the user provided labels. `Step.getLabel()` now returns an `Optional<String>`.
* Removed `UnionLinearStrategy`, `ChooseLinearStrategy`, and `RepeatLinearStrategy` as nested traversals are now natively supported in OLAP.
* Fixed `Neo4jGraph` around manual transaction behavior on `commit` and `rollback` such that they would throw exceptions if a transaction was not open.
* Redesigned the hidden step labeling mechanism so its consistent across a cluster, easier for rewrite strategies, and will enable nested OLAP traversals.
* `Traverser.incrLoops()` now takes a string step label to enable nested looping constructs (i.e. loop stacks).
* Added `Traversal.tryNext()` which returns an `Optional`, where the provided default method should be sufficient for all vendors.
* Removed `PathConsumer` in favor of `TraverserRequirement.PATH`-model via `Step.getRequirements()`.
* `Step.getRequirements()` returns a `Set<TraverserRequirement>` which is what is required of the `Traverser` by the `Step`.
* `Traverser` now extends `Cloneable` and `Traverser.clone()` is used to good effect in `Traverser.split()`.
* Added `AbstractTraverser` for which all traversers extend.
* Moved `Traversal.SideEffects` to `TraversalSideEffects` as sideEffects are not necessarily tied to the traversal.
* Removed `Graph.of()` for generating anonymous graph traversals -- replaced by `__`-model.
* Removed `Graph` being stored in `Traversal.SideEffects`. Too dangerous when moving between OLTP and OLAP and its limited uses were worked around easily.
* No need for `DefaultXXXGraphTraversal` unless the vendor is extending with new methods (e.g. `DefaultNeo4jGraphTraversal`).
* Reworked `TraversalStrategies` such that the are "emanating object class"-dependant, not `Traversal` dependent.
* Moved `Traverser.sideEffects()` to `Traverser.asAdmin().getSideEffects()`. Users should use `Traverser.sideEffects(key)` and `Traverser.sideEffects(key,value)`.
* Added `SerializationTest` to the `StructureStandardSuite` in `gremlin-test` which validates serialization at a lower level than `IoTest`.
* Removed `IntervalStep` and renamed `interval()` to `between()` which is simply an alias to a `has().has()` chain.
* Added `__` static interface which allows for `__.out().out()`-style construction of anonymous traversals (instead of `g.of()`).
* The only `GraphTraversal` steps that operate on `Traverser` are the base lambdas and `repeat()` (i.e. `emit()` and `until()`).
* Removed dependency on the `reflections` library in `gremlin-test` which removed the default implementation of `GraphProvider.getImplementations()` - vendors now need to implement this method themselves.
* Relaxed the `<S>` typing requirement for anonymous traversals when applied to `choose()`, `repeat()`, `union()`, etc.
* Removed `LoopStep` and `UntilStep` in favor of the new `RepeatStep` model of looping in Gremlin3.
* `BranchStep` is now exposed in `GraphTraversal` via `branch(function)`.
* `UnionStep` now implements `TraversalHolder`.
* Added `RepeatStep` as the new looping construct supporting do/while, while/do, and emit semantics.
* Moved `Traversal.sideEffects()` to `Traversal.Admin.getSideEffects()` as `cap()` should be used to access the sideEffect data of a traversal.
* Renamed vendor `XXXTraversal` to `XXXGraphTraversal` (interface) and `XXXGraphTraversal` to `DefaultXXXGraphTraversal` (implementation class).
* Modified packaging for console plugins to be more consistent by moving them to the `com.tinkerpop.gremlin.console.groovy.plugin` namespace.
* Removed all TinkerPop specific dependencies to Guava to avoid user version conflicts.
* Added support for `-e` (script file execution) and `-v` (version display) options on `gremlin.sh`.
* GraphSON supports the assignment of multiple custom serialization modules.
* `Traverser.get(stepLabel/sideEffectKey)` no longer exists. There now exists: `Traverser.path(stepLabel)` and `Traverser.sideEffects(sideEffectKey)`.
* `SimpleTraverser` now supports "path" but in a very loose, global cache way. Added `SparsePath` as a `Map`-backed `Path` implementation.
* Provided Neo4j multi-label support in Neo4j-Gremlin. Added three `Neo4jVertex`-specific methods: `addLabel()`, `removeLabel()`, `labels()`.
* Bumped to Groovy 2.3.9.
* Added `Graph.Io` interface which allows for simplified helper methods for end users and a way for vendors to override `GraphReader` and `GraphWriter` initial construction when custom serializers are needed.
* Removed methods from `GraphProvider` related to customizing serializers in `IoTest` from the test suite as the new `Graph.Io` interface now serves that purpose.
* Added `Neo4jGraph.checkElementsInTransaction(boolean)` which will (or not) verify whether elements retrieved via Neo4j global graph operations are transactionally consistent.
* Added `ScriptInputFormat` and `ScriptOutputFormat` to Hadoop-Gremlin for reading and writing a file according to an arbitrary parsing script.
* Added `TimeLimitStep.getTimedOut()` to determine if the step timed out or there were no more objects to process.
* `Graph.System` is now `Graph.Hidden` with "hidden" being the vendor namespace and the key prefix being `~`.
* Much better `toString()` handling in `Step` and `Traversal`.
* `ComparatorHolder<V>` interface returns a `List<Comparator<V>>` instead of a `Comparator<V>[]`.
* `T` now implements `Function<Element,Object>`.
* Added `ElementValueComparator` and `ElementFunctionComparator` in support of vendor introspection on `ComparatorHolder`-steps.
* Renamed `Comparing` marker interface to `ComparatorHolder`.
* `FunctionHolder` interface provides vendor introspection via `ElementValueFunction`.
* Removed `OrderByStep` as it is now just `order()` with a `by()`-based comparator.
* Added `SampleStep` (`sample()`) to allow for sampling the set of previous objects. Useful for doing random walks with `local()`.
* Renamed `random()` to `coin()` to better express that the filter is a random coin toss.
* Added `by()`-projection to modulate the meaning of post-processing steps like `aggregate()`, `groupCount()`, `path()`, `order()`, etc.
* Removed the `Strategy` interface and gave `StrategyGraph` direct access to the `GraphStrategy`.
* Added `Graph.strategy()` to help instantiate `StrategyGraph` instances.
* Modified the signature of all `GraphStrategy` methods to include an parameter that contains a reference to the "composing strategy".
* `PartitionStrategy` hides the specified partition key from view when iterating properties, keys, etc.
* Change construction of `GraphStrategy` implementations to be consistent with singleton instances and builder pattern.
* Added `Graph.Helper` annotation to "protected" certain default interface methods from implementation by vendors.
* Transaction retry functions now work with "manual" transactions.
* Improved error messaging when importing "legacy" GraphSON that was not generated with "extended" properties.
* Renamed "iterator" related methods in the `GraphStrategy` interface to be consistent with the method names they represent.
* `PropertyMapStep` (`valueMap()`) now takes a boolean to state if the tokens of the element are desired along with its properties.
* `HadoopGraph` now connected to the `StructureProcessSuite`.
* `HadoopGraph` no longer supports `Graph.Variables` as they were in-memory. A persistence mechanism can be introduced in the future.
* Hidden properties removed in favor of using `GraphStrategy` for such features.
* `Edge.iterators().vertexIterator(BOTH)` now guarantees `OUT` then `IN` vertex iterator order.
* `Graph.v(Object)` and `Graph.e(Object)` no longer exist. Instead, use `Graph.V(Object... ids)` and `Graph.E(Object... ids)`.
* Added `Graph.Iterators` to allow access to vertex and edge iterators based on element ids and bypassing `GraphTraversal`.
* Renamed `GraphStrategy` implementations to be less verbose - removed the word "Graph" from their names (e.g. `IdGraphStrategy` simply changed to `IdStrategy`).
* Removed `Step.NO_OBJECT` as the problem is solves can be solved with proper use of `flatMap` and `EmptyTraverser`.
* `Path` is now part of `GraphSerializer` and thus, not specific to a particular implementation of `Path`.
* Added messaging to show files being downloaded when using the Gremlin Server "install" command.
* Added test name and class arguments to the `GraphProvider.loadGraphWith` method.
* Merged `ReferencedXXX` and `DetachedXXX` so that all migration of graph element data is via `DetachedXXX`.
* Added `StaticVertexProgram` and `StaticMapReduce` which simply return `this` on `clone()`.
* `VertexProgram` and `MapReduce` now implement `Cloneable` and is used for fast copying across workers within the same machine.
* Added `TraversalHolder` interface which extends `PathConsumer` to determine recursively if nested traversals require path calculations turned on.
* Reworked how a `TraverserGenerator` is retrieved and utilized.
* Added `Traversal.toBulkSet()` to make getting resultant data more efficiently for traversals with repeated data.
* Provided a helper `LocalStep.isLocalStarGraph()` so `GraphComputer` implementers know the requisite data boundaries.
* Created `Traversal.Admin` to hide administrative methods. Added `Traversal.asAdmin()` to get at `Traversal.Admin`.
* Fixed up all `Step` cloning operations realizing that Java8 lambdas are always bound to the calling class (no delegates).
* Usage of `:remote close` without configured remotes shows a reasonable message rather than a stack trace.
* Provided `LocalStep` to signify that the internal traversal is locally bound to the incoming object.
* Failed script evaluation in Gremlin Server now triggers the cancel of the process attempting to timeout the script if it were to run too long.
* Greatly increased the speed of `ScriptEngineLambda` by making use of a static `ScriptEngine` cache.
* Fixed a general bug in all sideEffect using steps where the sideEffect should be accessed via the `Traverser` not `Traversal`.
* `GremlinPlugin` interface no longer has the `additionalDependencies` method - those dependencies are now defined by an entry in the manifest file for the jar called `Gremlin-Plugin-Dependencies`.
* Added `TinkerWorkerPool` which is used for resource efficient threading in `TinkerGraphComputer`.
* `MapReduce.createMapReduce(Configuration)` now exists and serves the same purpose as `VertexProgram.createVertexProgram(Configuration)`.
* Enabled SessionOps to be extended. Added eval handler hook.
* Setting a property with an unsupported data type throw `IllegalArgumentException` instead of `UnsupportedOperationException` as the operation is supported, but the argument is not.

=== TinkerPop 3.0.0.M6 (Release Date: December 2, 2014)

* `javatuples.Pair` avoided on `MapReduce` API in favor of a new `KeyValue` class.
* Renamed `Gremlin-Plugin` manifest entry for plugins to `Gremlin-Plugin-Paths`.
* Added `Gremlin-Plugin-Dependencies` manifest entry to list other dependencies that should be retrieved with a plugin jar.
* `Memory.Admin.asImmutable()` yields an immutable representation of the GraphComputer `Memory`.
* Fixed host selection in `gremlin-driver` by properly accounting for all hosts being marked unavailable at the instantiation of a `Client`.
* Removed Giraph-Gremlin in favor of new Hadoop-Gremlin with `GiraphGraphComputer` support. Future support for `MapReduceGraphComputer`.
* Greatly simplified the `InputFormat` and `OutputFormat` model for working with Giraph (and Hadoop).
* Added a serializer for `Property` for GraphSON correcting format of serialization of a single `Property` on an `Edge`.
* Fixed bug in Gremlin Console that prevented assignments to empty `List` objects.
* Added `VertexProgram.getMessageScopes()` to allow vendors to know which `MessageScopes` at a particular `Memory` state.
* Reduced the number of methods in `MessageScope.Local` as its up to vendors to inspect provided incident `Traversal` accordingly.
* Renamed `MessagesType` to `MessageScope` to make it less ambiguous regarding the class of the messages being sent.
* Changed the message type of `TraversalVertexProgram` to `TraverserSet` to support message combining.
* Added `VertexProgram.getMessageCombiner()` to support the combining of messages in route to a vertex.
* Reduced object creation in `TraversalVertexProgram` around vertex-local traversal sideEffects.
* Renamed `Traverser.Admin.makeChild()` and `Traverser.Admin.makeSibling()` to `Traverser.Admin.split()` to correspond with `merge()`.
* Added `Traverser.Admin.merge(Traverser)` method so that the merging algorithm is with the `Traverser`.
* Added `Operator` enum that contains sack-helpful `BinaryOperators`: sum, minus, mult, div, max, min, etc.
* Added `GraphTraversal.withSack()` and renamed `trackPaths()` and `with()` to `withPath()` and `withSideEffect()`, respectively.
* Added the "Gremlin Sacks" feature to allow a `Traverser` to carry local information along its walk.
* GraphSON format no longer makes use of `hiddens` JSON key. Its all just `properties`.
* Added `DoubleIterator` to make vendor implementations of `Edge.iterators().vertexIterator()` efficient.
* `PropertiesStep` is smart about hiddens vs. properties.
* `Element.iterators().hiddenProperties()` no longer exists. For vendors, simply provide an iterator of properties.
* `GIRAPH_GREMLIN_LIBS` supports colon separated directories for loading jars from multiple paths.
* Introduced method to control the location of dependencies dynamically loaded to the Gremlin Console as part of the `:install` command.
* Fixed problem with the Neo4j Gremlin Plugin not loading properly after Gremlin Console restart.
* Removed the "use" configuration from Gremlin Server.
* Moved `SugarGremlinPlugin` from `gremlin-console` to `gremlin-groovy` so that it could be shared with Gremlin Server.
* Fixed bug in serialization of `null` results returned to the Gremlin Console when serializing to strings.
* Moved the `GremlinPlugin` for `TinkerGraph` to `tinkergraph-gremlin` module (it is no longer in `gremlin-console`).
* Added a `plugin-info.txt` file to Gremlin Console `/ext/{module}` subdirectories to identify the module that was originally requested.
* Gremlin Server now allows for the explicit configuration of plugin activation.
* Refactored `GremlinPlugin` and `AbstractGremlinPlugin` to better account for plugins that run on the server and those that run in the console.
* Added a `plugins` configuration to Gremlin Server to control the plugins that are enabled on initialization.
* Added a builder option to `GremlinExecutor` to control the plugins that are enabled on initialization.
* Added `RemoteException` for usage with `RemoteAcceptor` implementations for the Gremlin Console so as to better standardize their development.
* Standardized all text being written to the Gremlin Console using starting upper case letter.
* Prevented error in the Console when `:submit` is called but no remotes were configured.
* Provided a way to clean the `grapes` directory as part of a standard build with `mvn clean install`.

=== TinkerPop 3.0.0.M5 (Release Date: November 7, 2014)

* Removed `PropertyFilterIterator` as using Java8 streams was just as efficient for the use case.
* Renamed `KryoWritable` to `GremlinWritable` as it is not necessarily Kryo that is the serialization mechanism.
* Fixed an input split bug in Giraph that was making it so that splits were not always at vertex boundaries.
* Fixed a combiner bug in `GirapGraphComputer`. Combiners were always calling `MapReduce.reduce()`, not `MapReduce.combine()`.
* Greatly simplified `SubgraphStrategy` by removing requirements for `Traversal` introspection.
* `StrategyWrappedGraph` mimics vendor use of `GraphStep` and `GraphTraversal` and no longer requires dynamic strategy application.
* `TraversalStrategies` make use of a dependency tree sorting algorithm to ensure proper sorts prior to application.
* `TraversalStrategies` are now immutable and are bound to the `Traversal` class.
* Fixed bug in Gephi Plugin that prevented it from communicating with the Gephi Streaming Server.
* Renamed `MessageType.XXX.to()` to `MessageType.XXX.of()` so it makes sense in both the sending and receiving context.
* Improved messaging with respect to tests that are ignored due to features to make it clear that those tests are not in error.
* Relaxed exception consistency checks in the test suite to only check that a thrown exception from an implementation extends the expected exception class (but no longer validates that it is the exact class or that the message text).
* `VertexProgram` now has `workerIterationStart()` and `workerIterationEnd()` to allow developers to control vertex split static data structures.
* `TraversalVertexProgram` startup time greatly reduced due to being smart about `loadState()` behavior.
* Gremlin Server sessions now allow serialization of results that were part of an open transaction.
* Refactor `OpProcessors` implementations in Gremlin Server for better reusability.
* `Vertex.iterators()` no longer have a `branchFactor`. This is now at the query language level with `localLimit()`.
* Added `limit(long)` and `localLimit(int,int)` which simply call the range equivalents with 0 as the low.
* Added `LocalRangeStep` which supports ranging the edges and properties of an element -- `localRange(int,int)`.
* `GraphTraversal.value(String)` no longer exists. Instead, use `GraphTraversal.values(String)`.
* `HiddenXXXStep` and `ValueXXXStep` no longer exist. `PropertyXXXStep` takes a `PropertyType` to denote value and hidden access.
* Added `PropertyType` to the structure-package which provide markers for denoting property types (vs. property classes).
* Renamed `setWorkingDirectory` to `workingDirectory` in the `KryoReader` builder.
* `Path.get(String)` returns the object if only one object is referenced by label, else it returns a `List` of referenced objects.
* Added overload to `GremlinKryo` to allow a serializer to be configured as a `Function<Kryo,Serializer>` to allow better flexibility in serializer creation.
* Added method to `GraphProvider` to allow implementers to provide a mechanism to convert GraphSON serialized identifiers back to custom identifiers as needed.
* Added methods to `GraphProvider` so that implementers could specify a custom built `GremlinKryo` class and/or `SimpleModule` class in case their implementation had custom classes to be serialized.
* Added `Traversal.forEachRemaining(class,consumer)` for those traversals whose end type is different from declared due to strategy rewriting.
* Removed `Traversal.forEach()` as traversal implements `Iterator` and users should use `forEachRemaining()`.
* `RangeStep` now has an inclusive low and an exclusive high -- a change from Gremlin2.
* `DriverGremlinPlugin` returns raw results with driver results available via the `result` variable.
* Removed test enforcement of `private` constructor for a `Graph` instance.
* `RemoteAcceptor` now supports `@` prefixed lines that will grab the script string from the Gremlin Console shell.
* Modified the signature of `Property.element()` to simply return `Element`
* Added `Reducing` marker and `ReducingStrategy` which supports reduction-functions as a final step in Gremlin OLAP (e.g. `fold()`).
* Once strategies are `complete()`, no more steps can be added to a `Traversal`.
* Renamed `Traversal.strategies()` to `Traversal.getStrategies()` as it is not a "query language"-method.
* Added test to enforce that a `label` on a `VertexProperty` is always set to the key of the owning property.
* Fixed bug with multi-property removal in `Neo4jGraph`.
* Bumped to Neo4j 2.1.5.
* Used standard `UUIDSerializer` from the `kryo-serializers` library for serialization of `UUID` objects.
* Changed GraphSON serialization to only use `iterators()` - there were still remnants of `Traversal` usage from previous refactoring.
* Added overload for `detach` method to allow for the `Element` to be detached as a "reference" only (i.e. without properties).
* Renamed `Item` in `gremlin-driver` to `Result`.
* Renamed `strategy` to `getStrategy` in `StrategyWrappedGraph`.
* Renamed `baseGraph` to `getBaseGraph` in `Neo4jGraph`.
* `Neo4jGraph` now returns an empty property `Vertex.property(k)` when the key is non-existent (a problem only visible when meta/multi property configuration was turned off).
* `Traversal.Strategies.apply()` now takes a `TraversalEngine`. Greatly simplifies strategy application for `STANDARD` or `COMPUTER`.
* Renamed `IdentityReductionStrategy` to `IdentityRemovalStrategy` for reasons of clarity.
* Added `ComparingRemovalStrategy` that removes `Comparing`-marked steps unless they are the end step of the traversal.
* `OrderStep` now works in OLAP, but only makes sense as a traversal end step.
* `MapReduce` API extended to include `getMapKeySort()` and `getReduceKeySort()` to sort outputs accordingly.
* Renamed `TraversalResultMapReduce` to `TraverserMapReduce`. Shorter and makes more sense.
* Improved build automation to package javadocs and asciidoc documentation in the distribution files.
* Improved build automation with a script to automatically bump release versions in the various files that needed it such as the `pom.xml` files.
* The identifier on `VertexProperty` is now read properly to those graphs that can support identifier assignment.
* `GraphSONReader.readGraph()` now properly reads vertex properties.
* Removed `Neo4jGraph.getCypher()` as users should use `Neo4jGraph.cypher()` and get back TinkerPop3 graph objects.
* `GiraphGraph.variables().getConfiguration()` is now replaced by `GiraphGraph.configuration()`.
* Added `Graph.configuration()` which returns the `Configuration` object of `Graph.open()`.
* Removed `TraverserTracker` as now there is only a `TraverserSet` for all halted traversers. A nice simplification of `TraversalVertexProgram`.
* Renamed `Traverser.isDone()` to `Traverser.isHalted()` and `DONE` to `HALT`. Consistent with automata terminology.
* Removed `PathTraverserExecutor` and `SimpleTraverserExecutor` as a single `TraverserExecutor` correctly executes both types of traversers.
* `TraversalVertexProgram` does "reflexive message passing" to reduce the total number of iterations required to execute a traversal.
* `MapReduce` no-argument constructors are private and thus, only for reflection and `loadState()` usage.
* MapReducers for `TraversalVertexProgram` are now smart about `with()` declared data structures.
* Updated `Traversal.SideEffects` to use "registered suppliers" and it now works accordingly in both OLTP and OLAP environments.
* Increased the speed of `FlatMapStep` by approximately 1.5x.

=== TinkerPop 3.0.0.M4 (Release Date: October 21, 2014)

* Added features for `VertexProperty` user supplied ids and related data types.
* Removed `SideEffectCap` marker interface as there is only one `SideEffectCapStep` and thus, `instanceof` is sufficient.
* `Path.getObjects()`/`Path.getLabels()` renamed to `Path.objects()`/`Path.labels()` to be in line with "query language" naming convention.
* Greatly simplified `GiraphInternalVertex` due to `Element.graph()` -- 1/2 the memory footprint and reduced construction time.
* Renamed `Property.getElement()` to `Property.element()` given the "query language" naming convention.
* `Element.graph()` added which returns the `Graph` that the element is contained within.
* Added tests for greater consistency around iterating hidden properties.
* Simplified `TraversalVertexProgram` where only a single `TraverserTracker` exists for both path- and simple-traversers.
* Fixed a major bug where `Arrays.binarySearch` was being used on an unsorted array in TinkerGraph and Neo4jGraph.
* Changed `ComputerResult.getXXX()` to `graph()` and `memory()` to be consistent with "query language" naming convention.
* `Traverser.getXXX()` changed to `loops()`, `bulk()`, `path()`, `sideEffects()` to be consistent with "query language" naming convention.
* Optimization to reduce the number of empty lists created due to no step class existing for respective `TraversalStrategy.apply()`.
* Added `CapTraversal` as a marker interface for the `cap()` method.
* Added `union()` with GraphComputer `UnionLinearStrategy`.
* `TimeLimitStep` was moved to `filter/` package. It was a mistake that it was in `sideEffect/`.
* Provided the configuration for generating both a "full" and "core" set of javadocs, where "full" represents all classes in all projects and "core" is the "user" subset.
* Validated bindings passed to Gremlin Server to ensure that they do not match the most common statically imported values.
* If no script engine name is provided to a `LambdaHolder` it is assumed to be Gremlin-Groovy.
* `MapEmitter` and `ReduceEmitter` have an `emit(value)` default method where the key is the `MapReduce.NullObject` singleton.
* `Traverser.Admin` now implements `Attachable` as the `Traversal.SideEffects` can be generated from the `Vertex`.
* Made a solid effort to ensure that all TinkerPop keys are `Graph.System` to leave `Graph.Key` for users.
* The `Graph.System` prefix is now `^` instead of `%&%`. Simpler and easier on the `toString()`-eyes.
* Added `Traversal.SideEffects.ifPresent(Consumer)` as a default helper method.
* Added `profile()`-step which provides detailed information about the performance of each step in a traversal.
* No more `CountCapStep` and `CountStep`, there is only `CountStep` and it is elegant.
* Created a `AbstractTraversalStrategy` with good `toString()`, `hasCode()`, and `equals()` implementations.
* Added `CountTraversal` as a marker-interface stating that the `Traversal` has a `count() -> Long` method.
* `Traversal` no longer has any step methods as its not required for DSL implementers to have "core steps."
* Added "linearization" strategy for `ChooseStep` so it is executed correctly on GraphComputer.
* Added `GraphTraversalStrategyRegistry` which has respective global strategies to make turning on/off strategies easier.
* Added a generic `BranchStep` to be used for re-writing "meta-steps" for execution on GraphComputer.
* Moved `JumpStep`, `UntilStep`, and `ChooseStep` to a new `branch/` package.
* Added test cases to the Structure Suite to enforce consistent operations of reading properties after removal of their owning `Element`.
* GraphSON format change for full `Graph` serialization - Graph variables are now serialized with the key "variables" as opposed to "properties".
* Relaxed `Graph.toString()` test requirements for implementers.
* Made the `toString` operations in `GraphStrategy` consistent.
* Added `VertexFeatures.supportsRemoveProperty`.
* Added `VertexPropertyFeatures.supportsRemoveProperty`.
* Added `EdgeFeatures.supportsRemoveProperty`.
* Added `VertexFeatures.supportsRemoveVertices`.
* Added `EdgeFeatures.supportsRemoveEdges`.
* Vendors should now get a clear error when mis-spelling something in an `@OptOut` (or more likely if a test name changes) and it now works all the test suites.
* All plugins now have a default prefix of "tinkerpop." as a namespace.
* `GraphComputer` now executes a `Set<MapReduce>` and `hashCode()`/`equals()` were implemented for existing `MapReduce` implementations.
* Changed `Contains.in/notin` to `Contains.within/without` as `in` is a reserved term in most languages (including Java and Groovy).
* Added helper methods for loading data into collections in `TraversalHelper`.
* Core `Traversal` methods are smart about bulking -- e.g. `iterate()`, `fill()`, `remove()`, etc.
* `GroupByStep` and `GroupByMapReduce` leverage `BulkSet` as the default group data structure.
* `Element.Iterator` has renamed methods so implementers can do `MyElement implements Element, Element.Iterators`.
* Renamed `MessageType.Global` and `MessageType.Local` creators from `of()` to `to()` as it makes more sense to send messages `to()`.
* With `Traverser.get/setBulk()` there is no need for a `TraverserMessage`. The `Traverser` is now the message in `TraversalVertexProgram`.
* Provided static `make()` methods for constructing `Path` implementations.
* Provided a more space/time efficient algorithm for `Path.isSimple()`.
* The `JumpStep` GraphComputer algorithm `Queue` is now a `TraverserSet`.
* `AggregateStep` and `StoreStep` now use `BulkSet` as their default backing `Collection` (much more space/time efficient).
* Added `BulkSet` which is like `TraverserSet` but for arbitrary objects (i.e. a weighted set).
* `UnrollJumpStrategy` is no longer a default strategy as it is less efficient with the inclusion of `TraverserSet`.
* Introduced `TraverserSet` with bulk updating capabilities. Like OLAP, OLTP looping is now linear space/time complexity.
* TinkerGraph's MapReduce framework is now thread safe with a parallel execution implementation.
* Added a default `Traverser.asAdmin()` method as a typecast convenience to `Traverser.Admin`.
* Renamed `Traverser.System` to `Traverser.Admin` as to not cause `java.lang.System` reference issues.
* Renamed `Memory.Administrative` to `Memory.Admin` to make it shorter and consistent with `Traverser.Admin`.
* Fixed a TinkerGraph bug around user supplied vertex property ids.
* Most `Step` classes are now defined as `public final class` to prevent inheritance.
* `ShuffleStep` now extends `BarrierStep` which enables semantically correct step-sideEffects.
* Leveraged `Traverser.getBulk()` consistently throughout all steps.

=== TinkerPop 3.0.0.M3 (Release Date: October 6, 2014)

* All `Step` fields are now `private`/`protected` with respective getters as currently needed and will be added to as needed.
* Gremlin Server no longer has the `traverse` operation as lambdas aren't really serialized.
* `Path` is now an interface with `ImmutablePath` and `MutablePath` as implementations (2x speedup on path calculations).
* `Traverser` now implements `Comparable`. If the underlying object doesn't implement `Comparable`, then a runtime exception.
* Added abstract `BarrierStep` which greatly simplifies implementing barriers like `AggregateStep`, `OrderStep`, etc.
* `SelectStep` is now intelligent about when to trigger path computations based on label selectors and barriers.
* `T` no longer has `eq`, `neq`, `lt`, `in`, etc. Renamed all respective enums and with `static import`, good in console (e.g. `Compare.eq`).
* Added `Order` enum which provides `Order.decr` and `Order.incr`.
* `Traverser.loops` and `Jump.loops` are now shorts (`32767` max-loops is probably sufficient for 99.9999% of use cases).
* `Traverser.bulk` exists which is how many instances does the traverser represent. For use in grouping with bulk computations.
* Greatly simplified sideEffect steps where there is no distinction between OLAP vs. OLTP (from the `Step` perspective).
* Removed the need for `Bulkable` and `VertexCentric` marker interfaces in process API.
* Renamed configuration parameters in Giraph-Gremlin to be consistent with a `giraph.gremlin`-prefix.
* Made it possible to pass a `ScriptEngine` name and string script in `TraversalVertexProgram` and `LambdaVertexProgram`.
* Made `TinkerGraph` a plugin for the Console as it is no longer a direct dependency in `gremlin-groovy`.
* Added features for supporting the addition of properties via `Element.property(String,Object)`.
* `GiraphGraph` OLTP tested against Gremlin-Java8 and Gremlin-Groovy -- OLAP tested against Gremlin-Groovy.
* `Neo4jGraph` is now tested against both Gremlin-Java8 and Gremlin-Groovy.
* Renamed the test cases in `ProcessTestSuite` to be consistent with other Gremlin language variants.
* Added a `gremlin-groovy-test` suite that can be used to validate implementations against the Groovy variant of Gremlin.
* `TinkerGraph` is no longer serializable, use a `GraphReader`/`GraphWriter` to serialize the graph data.
* Removed `implements Serializable` on numerous classes to ensure safety and proper usage of utilities for cloning.
* `Traversal` now implements `Cloneable` as this is the means that inter-JVM threads are able to get sibling `Traversals`.
* Created "integration" test for `Neo4jGraph` that runs the test suite with multi/meta property features turned off.
* Added `GraphStrategy` methods for `VertexProperty`.
* Converted the `id` data type from string to integer in the Grateful Dead sample data.
* Removed all notions of serializable lambdas as this is a misconception and should not be part of TinkerPop.
* Greatly simplified `TraversalVertexProgram` with three arguments: a `Traversal<Supplier>`, `Class<Traversal<Supplier>>`, or a script string with `ScriptEngine` name.
* Added `TraversalScript` interface with `GroovyTraversalScript` as an instance. To be used by OLAP engines and any language variant (e.g. gremlin-scala, gremlin-js, etc.).
* `UntilStep` now leverages `UnrollJumpStrategy` accordingly.
* Fixed a bug where the `toString()` of `Traversal` was being hijacked by `SugarGremlinPlugin`.
* Fixed compilation bug in `UntilStep` that is realized when used in multi-machine OLAP.
* Simplified `Enumerator` and implementations for `MatchStep`.

=== TinkerPop 3.0.0.M2 (Release Date: September 23, 2014)

* Added an exhaust `InnerJoinEnumerator` fix in `MatchStep` to get all solutions correctly.
* `Neo4jGraph` can be configured to allow or disallow meta- and multi-properties.
* Added `until()`-step as a simpler way to express while-do looping which compiles down to a `jump()`-step equivalent.
* Added "The Crew" (`CREW`) toy graph which contains multi-properties, meta-properties, graph variables, hiddens, etc.
* If the Giraph job fails, then the subsequent `MapReduce` jobs will not execute.
* Added `Graph.System` class which generates keys prefixed with `%&%` which is considered the vendor namespace and not allowed by users.
* Added `ReferencedVertex` (etc. for all graph object types) for lightweight message passing of graph object ids.
* `T.*` now has `label`, `id`, `key`, `value` and no longer are these `String` representations reserved in TinkerPop.
* `Traverser` now has a transient reference to `Traversal.SideEffects`.
* "Detached" classes are now tested by the standard test suite.
* Compartmentalized `Traverser` interface so there is now a `Traverser.System` sub-interface with methods that users shouldn't call.
* Added `OrderByStep` which orders `Elements` according to the value of a provided key.
* 2x speed increase on steps that rely heavily on `ExpandableStepIterator` with massive memory footprint reduction as well.
* Added `VertexProperty<V>` as the property type for vertices -- provides multi-properties and properties on properties for vertices.
* Changed `VertexProgram` such that `getElementComputeKeys()` is simply a `Set<String>`.
* Significant changes to the format of the `ResponseMessage` for Gremlin Server - these changes break existing clients.
* Close any open transactions on any configured `Graph` when a session in Gremlin Server is killed.
* Grateful Dead Graph now uses vertex labels instead of "type" properties.
* There is now a `GraphComputerStrategy` and `EngineDependent` marker interface to allow steps to decide their algorithm depending if they are OLAP or OLTP.
* A labeled step now stores its current traverser value in `Traversal.SideEffects` (no longer can sideEffectKeys and step labels be the same).
* `GraphFactory` support for opening a `Graph` with multiple `GraphStrategy` instances - if there are multiple strategies they are wrapped in order via `SequenceGraphStrategy`.
* The result type for result termination messages returned from Gremlin Server is now set to "no content".
* The `maxContentLength` setting for Gremlin Driver now blocks incoming frames that are too large.
* After initialization scripts are executed in Gremlin Server, the `Graph` instances are re-bound back to their global references, thus allowing `GraphStrategy` initialization or even dynamic `Graph` creation through scripts.
* Added "Modern" graph back which is basically the "Classic" graph with double values for the "weight" property on edges and non-default vertex labels.
* `Traversal.addStep()` is now hard typed so type casting isn't required and traversal APIs look clean.
* Changed the hidden key prefix from `%$%` to `~` in `Graph.Key.hide()`.
* Added `has(label,key,predicate,value)` to allow for `has('person','name','marko')`. Various overloaded methods provided.
* Update to traversal API where if a `SFunction<S,?>` was required, but can process a `Traverser<S>`, then the function is `SFunction<Traverser<S>,?>`.
* Added `WhereStep` as a way to further constrain `select()` and `match()`.
* Extensive work on `GiraphMemory` and its interaction with Giraph aggregators.
* If the input path of a `GiraphGraphComputer` does not exist, failure happens prior to job submission.
* `SugarPlugin` now has all inefficient methods and Gremlin-Groovy proper is only efficient Groovy techniques.
* Prevented concurrency problems by only modifying bindings within the same thread of execution in the `GremlinExecutor`.
* Calls to `use` on the `DependencyManager` now return the list of `GremlinPlugin` instances to initialize instead of just initializing them automatically because it causes problems with `ScriptEngine` setup if a plugin requires a script to be evaluated and a required dependency is not yet loaded.
* `Traversal.SideEffects` has `getGraph()`, `setGraph()`, and `removeGraph()` default helpers.
* `Traversal.Memory` -> `Traversal.SideEffects` and `GraphComputer.SideEffects` -> `GraphComputer.Memory`.
* `StrategyWrappedVertex` and `StrategyWrappedEdge` properly wrap `Element` objects returned from non-traversal based methods.
* Gremlin-Server now sends a single write with status 200 for Object and empty response messages.
* `GremlinGroovyScriptEngine` allows imports to re-import dependencies added via "use".
* Changed order in which the `GremlinExecutor` is initialized such that dependency loading via "use" are handled first which fixes problems with starting Gremlin Server with `gremlin-server-neo4j.yaml`.
* Corrected issues with the "branch factor" related traversals under `SubgraphStrategy`.  This change also altered the semantics of the `SubgraphStrategy` a bit as it became more restrictive around `Edge` inclusion (requires both vertices to be in the subgraph).
* The Gephi Plugin now visualizes traversals and has numerous configuration options.
* Added more specific features around the types of "identifiers" a graph can support.
* Added a new test graph called `MODERN` that is copy of the `CLASSIC` graph, but represents floats as doubles.  This graph will be the default graph for testing going forward.
* Fix bug in `Neo4jGraph` that was not processing multiple vertex labels properly when doing a `has()` step with `IN`.
* Changed semantics of `@LoadGraphWith` in gremlin-test to only refer to the ability of a test implementation to process the data types of the test graph (not to actually load it).
* `StartStep` is a `SideEffect` as it is a process to get data into the stream (like a keyboard) and more efficient as such.
* Greatly simplified the implementations of `Map`, `FlatMap`, `Filter`, and `SideEffect`.
* `Path` data structure changed to an ordered list of objects with each associated to a `Set<String>` of as-labels.
* All sideEffect-based steps no longer extend `FilterStep` with predicate equal true, but a more efficient `SideEffectStep`.
* `TreeStep` now has `TreeMapReduce` for executing on `GraphComputer`.
* `Neo4jTraversal.cypher()` is fluent throughout.
* Reverted back to TP2 model of `as()` referring to step names, not variable names of sideEffects.
* Updated `AddEdge`-step to support property key/value pairs for appending to newly created edges.
* Renamed `Graph.getFeatures()` to `Graph.features()` to be consistent with other API methods.
* `Vertex` and `Edge` now implement all `GraphTraversal` methods to ensure consistency throughout stack.
* `Neo4jTraversal` is auto-generated from `Neo4jTraversalStub` with technique generalizable to other vendors.
* Added test suite to ensure that all traversals are of the same type: `g.V`, `g.E`, `g.of()`, `v.identity()`, `e.identity()`, v-, e-methods.
* Giraph HDFS helpers now support `hdfs.mkdir(string)` and `local.mkdir(string)`
* Added `@OptIn` and `@OptOut` for implementers to specify on their `Graph` implementations for test compliance information.
* `GraphComputer` `Memory` now immutable after computation is complete.
* Dependency grabbing for plugins filter out slf4j logging dependencies so as to avoid multiple bindings with the standard TinkerPop distributions.
* Fixed `GiraphMemory` to be fully consistent with GraphComputer specification.
* Removed fatJar assembly from Giraph-Graph as it is no longed needed with distributed cache model.
* Reworked `GiraphRemoteAcceptor` to provide a `result` variable back to the console with `ComputerResult`.
* `VertexProgram` is no longer `Serializable` (use `loadState` and `storeState` for wire-propagation).
* Moved `GiraphGraph.getOutputGraph()` to `GiraphHelper`.
* Changed `GIRAPH_GREMLIN_HOME` to `GIRAPH_GREMLIN_LIB` to reference directory where jars are to be loaded.
* Updated README with release instructions.

=== TinkerPop 3.0.0.M1 (Release Date: August 12, 2014)

* First official release of TinkerPop3 and thus, no changes.
