
# Configuration Options
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| Key | Type | Description | Default Value | Since | Supports Repo ID suffix | Source |
| --- | --- | --- | --- | --- | --- | --- |
| `"aether.artifactResolver.postProcessor.trustedChecksums"` | `Boolean` | Is post processor enabled. |  `false`  | 1.9.0 |  No  | Session Configuration |
| `"aether.artifactResolver.postProcessor.trustedChecksums.checksumAlgorithms"` | `String` | The checksum algorithms to apply during post-processing as comma separated list. |  `"SHA-1"`  | 1.9.0 |  No  | Session Configuration |
| `"aether.artifactResolver.postProcessor.trustedChecksums.failIfMissing"` | `Boolean` | Should post processor fail resolution if checksum is missing? |  `false`  | 1.9.0 |  No  | Session Configuration |
| `"aether.artifactResolver.postProcessor.trustedChecksums.record"` | `Boolean` | Should post processor go into "record" mode (and collect checksums instead of validate them)? |  `false`  | 1.9.0 |  No  | Session Configuration |
| `"aether.artifactResolver.postProcessor.trustedChecksums.scope"` | `String` | The scope to apply during post-processing. Accepted values are <code>all</code> (is default and is what happened before), and <code>project</code> when the scope of verification are project dependencies only (i.e. plugins are not verified). |  `"all"`  | 2.0.11 |  No  | Session Configuration |
| `"aether.artifactResolver.postProcessor.trustedChecksums.snapshots"` | `Boolean` | Should post processor process snapshots as well? |  `false`  | 1.9.0 |  No  | Session Configuration |
| `"aether.artifactResolver.simpleLrmInterop"` | `Boolean` | Configuration to enable "interoperability" with Simple LRM, but this breaks RRF feature, hence this configuration is IGNORED when RRF is used, and is warmly recommended to leave it disabled even if no RRF is being used. |  `false`  |  |  No  | Session Configuration |
| `"aether.artifactResolver.snapshotNormalization"` | `Boolean` | Configuration to enable "snapshot normalization", downloaded snapshots from remote with timestamped file names will have file names converted back to baseVersion. It replaces the timestamped snapshot file name with a filename containing the SNAPSHOT qualifier only. This only affects resolving/retrieving artifacts but not uploading those. |  `true`  |  |  No  | Session Configuration |
| `"aether.chainedLocalRepository.ignoreTailAvailability"` | `Boolean` | When using chained local repository, should be the artifact availability ignored in tail. |  `true`  | 1.9.2 |  No  | Session Configuration |
| `"aether.checksums.omitChecksumsForExtensions"` | `String` | Comma-separated list of extensions with leading dot (example ".asc") that should have checksums omitted. These are applied to sub-artifacts only. Note: to achieve 1.7.x aether.checksums.forSignature=true behaviour, pass empty string as value for this property. |  `".asc,.sigstore,.sigstore.json"`  |  |  No  | Session Configuration |
| `"aether.conflictResolver.impl"` | `String` | The name of the conflict resolver implementation to use: "path" (default) or "classic" (same as Maven 3). |  `"path"`  | 2.0.11 |  No  | Session Configuration |
| `"aether.conflictResolver.path.showCyclesInStandardVerbosity"` | `Boolean` | This implementation of conflict resolver is able to show more precise information regarding cycles in standard verbose mode. But, to make it really drop-in-replacement, we "tame down" this information. Still, users needing it may want to enable this for easier cycle detection, but in that case this conflict resolver will provide "extra nodes" not present on "standard verbosity level" with "classic" conflict resolver, that may lead to IT issues down the stream. Hence, the default is to provide as much information as much verbose "classic" does. |  `false`  | 2.0.12 |  No  | Session Configuration |
| `"aether.conflictResolver.verbose"` | `Object` | The key in the repository session's <code>org.eclipse.aether.RepositorySystemSession#getConfigProperties() configuration properties</code> used to store a <code>Boolean</code> flag controlling the transformer's verbose mode. Accepted values are Boolean types, String type (where "true" would be interpreted as <code>true</code> ) or Verbosity enum instances. |  `"NONE"`  |  |  No  | Session Configuration |
| `"aether.conflictResolver.versionSelector.selectionStrategy"` | `String` | The name of the version selection strategy to use in conflict resolution: "nearest" (default) or "highest". |  `"nearest"`  | 2.0.11 |  No  | Session Configuration |
| `"aether.connector.basic.downstreamThreads"` | `Integer` | Number of threads in basic connector for downloading. |  `5`  | 2.0.0 |  Yes  | Session Configuration |
| `"aether.connector.basic.parallelPut"` | `Boolean` | Enables or disables parallel PUT processing (parallel deploys) on basic connector globally or per remote repository. When disabled, connector behaves exactly as in Maven 3.8.x did: GETs are parallel while PUTs are sequential. |  `true`  | 1.9.5 |  Yes  | Session Configuration |
| `"aether.connector.basic.persistedChecksums"` | `Boolean` | Flag indicating whether checksums which are retrieved during checksum validation should be persisted in the local repository next to the file they provide the checksum for. |  `true`  | 0.9.0.M4 |  No  | Session Configuration |
| `"aether.connector.basic.smartChecksums"` | `Boolean` | Flag indicating that instead of comparing the external checksum fetched from the remote repo with the calculated one, it should try to extract the reference checksum from the actual artifact response headers This only works for HTTP transports. |  `true`  | 0.9.0.M3 |  No  | Session Configuration |
| `"aether.connector.basic.threads"` | `Integer` | Number of threads in basic connector for uploading/downloading. Observed only if some of the upstream or downstream threads are not set. (Deprecated) |  `5`  | 0.9.0.M4 |  No  | Session Configuration |
| `"aether.connector.basic.upstreamThreads"` | `Integer` | Number of threads in basic connector for uploading. |  `5`  | 2.0.0 |  Yes  | Session Configuration |
| `"aether.dependencyCollector.bf.skipper"` | `String` | The key in the repository session's <code>RepositorySystemSession#getConfigProperties() configuration properties</code> used to store a <code>String</code> flag controlling the resolver's skip mode. Supported modes are "versionless" (default), "versioned" and "false" to not use skipper. The first two modes are defining "function" how to map artifact coordinates to (String) key while deciding "skip" logic. The "versionless" uses <code>G:A:C:E</code> coordinate elements only (without version), while "versioned" uses all <code>G:A:C:E:V</code> artifact coordinates. |  `"versionless"`  | 1.8.0 |  No  | Session Configuration |
| `"aether.dependencyCollector.bf.threads"` | `Integer` | The count of threads to be used when collecting POMs in parallel. |  `5`  | 1.9.0 |  No  | Session Configuration |
| `"aether.dependencyCollector.impl"` | `String` | The name of the dependency collector implementation to use: depth-first (original) named "df", and breadth-first (new in 1.8.0) named "bf". Both collectors produce equivalent results, but they may differ performance wise, depending on project being applied to. Our experience shows that existing "df" is well suited for smaller to medium size projects, while "bf" may perform better on huge projects with many dependencies. Experiment (and come back to us!) to figure out which one suits you the better. |  `"bf"`  | 1.8.0 |  No  | Session Configuration |
| `"aether.dependencyCollector.maxCycles"` | `Integer` | Only up to the given amount cyclic dependencies are emitted. |  `10`  | 1.8.0 |  No  | Session Configuration |
| `"aether.dependencyCollector.maxExceptions"` | `Integer` | Only exceptions up to the number given in this configuration property are emitted. Exceptions which exceed that number are swallowed. |  `50`  | 1.8.0 |  No  | Session Configuration |
| `"aether.dependencyCollector.pool.artifact"` | `String` | Flag controlling interning data pool type used by dependency collector for Artifact instances, matters for heap consumption. By default, uses “weak” references (consume less heap). Using “hard” will make it much more memory aggressive and possibly faster (system and Java dependent). Supported values: "hard", "weak". |  `"weak"`  | 1.9.5 |  No  | Session Configuration |
| `"aether.dependencyCollector.pool.dependency"` | `String` | Flag controlling interning data pool type used by dependency collector for Dependency instances, matters for heap consumption. By default, uses “weak” references (consume less heap). Using “hard” will make it much more memory aggressive and possibly faster (system and Java dependent). Supported values: "hard", "weak". |  `"weak"`  | 1.9.5 |  No  | Session Configuration |
| `"aether.dependencyCollector.pool.dependencyLists"` | `String` | Flag controlling interning data pool type used by dependency lists collector for ArtifactDescriptor (POM) instances, matters for heap consumption. By default, uses “weak” references (consume less heap). Using “hard” will make it much more memory aggressive and possibly faster (system and Java dependent). Supported values: "hard", "weak". |  `"hard"`  | 1.9.22 |  No  | Session Configuration |
| `"aether.dependencyCollector.pool.descriptor"` | `String` | Flag controlling interning data pool type used by dependency collector for ArtifactDescriptor (POM) instances, matters for heap consumption. By default, uses “weak” references (consume less heap). Using “hard” will make it much more memory aggressive and possibly faster (system and Java dependent). Supported values: "hard", "weak". |  `"hard"`  | 1.9.5 |  No  | Session Configuration |
| `"aether.dependencyCollector.pool.internArtifactDescriptorDependencies"` | `Boolean` | Flag controlling interning artifact descriptor dependencies. |  `false`  | 1.9.22 |  No  | Session Configuration |
| `"aether.dependencyCollector.pool.internArtifactDescriptorManagedDependencies"` | `Boolean` | Flag controlling interning artifact descriptor managed dependencies. |  `true`  | 1.9.22 |  No  | Session Configuration |
| `"aether.dependencyManager.verbose"` | `Boolean` | The key in the repository session's <code>org.eclipse.aether.RepositorySystemSession#getConfigProperties() configuration properties</code> used to store a <code>Boolean</code> flag controlling the verbose mode for dependency management. If enabled, the original attributes of a dependency before its update due to dependency management will be recorded in the node's <code>DependencyNode#getData() custom data</code> when building a dependency graph. |  `false`  |  |  No  | Session Configuration |
| `"aether.generator.gpg.agentSocketLocations"` | `String` | The GnuPG agent socket(s) to try. Comma separated list of socket paths. If relative, will be resolved from user home directory. |  `".gnupg/S.gpg-agent"`  | 2.0.0 |  No  | Session Configuration |
| `"aether.generator.gpg.enabled"` | `Boolean` | Whether GnuPG signer is enabled. |  `false`  | 2.0.0 |  No  | Session Configuration |
| `"aether.generator.gpg.keyFilePath"` | `String` | The path to the OpenPGP transferable secret key file. If relative, is resolved from local repository root. |  `"maven-signing-key.key"`  | 2.0.0 |  No  | Session Configuration |
| `"aether.generator.gpg.keyFingerprint"` | `String` | The PGP Key fingerprint as hex string (40 characters long), optional. If not set, first secret key found will be used. |  -  | 2.0.0 |  No  | Session Configuration |
| `"aether.generator.gpg.useAgent"` | `Boolean` | Whether GnuPG agent should be used. |  `true`  | 2.0.0 |  No  | Session Configuration |
| `"aether.generator.sigstore.enabled"` | `Boolean` | Whether Sigstore signer is enabled. |  `false`  | 2.0.2 |  No  | Session Configuration |
| `"aether.generator.sigstore.publicStaging"` | `Boolean` | Whether Sigstore should use public staging <code>sigstage.dev</code> instead of public default <code>sigstore.dev</code> . |  `false`  | 2.0.2 |  No  | Session Configuration |
| `"aether.interactive"` | `Boolean` | A flag indicating whether interaction with the user is allowed. |  `false`  |  |  No  | Session Configuration |
| `"aether.layout.maven2.checksumAlgorithms"` | `String` | Comma-separated list of checksum algorithms with which checksums are validated (downloaded) and generated (uploaded) with this layout. Resolver by default supports following algorithms: MD5, SHA-1, SHA-256 and SHA-512. New algorithms can be added by implementing ChecksumAlgorithmFactory component. |  `"SHA-1,MD5"`  | 1.8.0 |  Yes  | Session Configuration |
| `"aether.lrm.enhanced.localPrefix"` | `String` | The prefix to use for locally installed artifacts. |  `"installed"`  | 1.8.1 |  No  | Session Configuration |
| `"aether.lrm.enhanced.releasesPrefix"` | `String` | The prefix to use for release artifacts. |  `"releases"`  | 1.8.1 |  No  | Session Configuration |
| `"aether.lrm.enhanced.remotePrefix"` | `String` | The prefix to use for remotely cached artifacts. |  `"cached"`  | 1.8.1 |  No  | Session Configuration |
| `"aether.lrm.enhanced.snapshotsPrefix"` | `String` | The prefix to use for snapshot artifacts. |  `"snapshots"`  | 1.8.1 |  No  | Session Configuration |
| `"aether.lrm.enhanced.split"` | `Boolean` | Whether LRM should split local and remote artifacts. |  `false`  | 1.8.1 |  No  | Session Configuration |
| `"aether.lrm.enhanced.splitLocal"` | `Boolean` | Whether locally installed artifacts should be split by version (release/snapshot). |  `false`  | 1.8.1 |  No  | Session Configuration |
| `"aether.lrm.enhanced.splitRemote"` | `Boolean` | Whether cached artifacts should be split by version (release/snapshot). |  `false`  | 1.8.1 |  No  | Session Configuration |
| `"aether.lrm.enhanced.splitRemoteRepository"` | `Boolean` | Whether cached artifacts should be split by origin repository (repository ID). |  `false`  | 1.8.1 |  No  | Session Configuration |
| `"aether.lrm.enhanced.splitRemoteRepositoryLast"` | `Boolean` | For cached artifacts, if both splitRemote and splitRemoteRepository are set to true sets the splitting order: by default it is repositoryId/version (false) or version/repositoryId (true) |  `false`  | 1.8.1 |  No  | Session Configuration |
| `"aether.lrm.enhanced.trackingFilename"` | `String` | Filename of the file in which to track the remote repositories. |  `"_remote.repositories"`  |  |  No  | Session Configuration |
| `"aether.metadataResolver.threads"` | `Integer` | Number of threads to use in parallel for resolving metadata. |  `4`  | 0.9.0.M4 |  No  | Session Configuration |
| `"aether.named.diagnostic.enabled"` | `Boolean` | System property key to enable locking diagnostic collection. |  `false`  | 1.9.11 |  No  | Java System Properties |
| `"aether.named.file-lock.attempts"` | `Integer` | Tweak: on Windows, the presence of <em>StandardOpenOption#DELETE_ON_CLOSE</em> causes concurrency issues. This flag allows to implement similar fix as referenced JDK bug report: retry and hope the best. Default value is 5 attempts (will retry 4 times). |  `5`  | 1.7.3 |  No  | Java System Properties |
| `"aether.named.file-lock.deleteLockFiles"` | `Boolean` | Tweak: on Windows, the presence of <em>StandardOpenOption#DELETE_ON_CLOSE</em> causes concurrency issues. This flag allows to have it removed from effective flags, at the cost that lockfile directory becomes crowded with 0 byte sized lock files that are never cleaned up. Default value is <code>true</code> on non-Windows OS. See <a href="https://bugs.openjdk.org/browse/JDK-8252883">JDK-8252883</a> for Windows related bug. Users on Windows can still force "delete on close" by explicitly setting this property to <code>true</code> . |  `true`  | 1.7.3 |  No  | Java System Properties |
| `"aether.named.file-lock.sleepMillis"` | `Long` | Tweak: When <code>#SYSTEM_PROP_ATTEMPTS</code> used, the amount of milliseconds to sleep between subsequent retries. Default value is 50 milliseconds. |  `50`  | 1.7.3 |  No  | Java System Properties |
| `"aether.named.ipc.debug"` | `Boolean` | Should the IPC server log debug messages? (i.e. for testing purposes) |  `false`  | 2.0.1 |  No  | Java System Properties |
| `"aether.named.ipc.family"` | `String` | IPC socket family to use. |  `"unix"`  | 2.0.1 |  No  | Java System Properties |
| `"aether.named.ipc.idleTimeout"` | `Integer` | IPC idle timeout in seconds. If there is no IPC request during idle time, it will stop. |  `300`  | 2.0.1 |  No  | Java System Properties |
| `"aether.named.ipc.nativeName"` | `String` | The name if the IPC server native executable (without file extension like ".exe") |  `"ipc-sync"`  | 2.0.1 |  No  | Java System Properties |
| `"aether.named.ipc.nofork"` | `Boolean` | Should the IPC server not fork? (i.e. for testing purposes) |  `false`  | 2.0.1 |  No  | Java System Properties |
| `"aether.named.ipc.nonative"` | `Boolean` | Should the IPC server not use native executable? |  `true`  | 2.0.1 |  No  | Java System Properties |
| `"aether.offline.hosts"` | `String` | Comma-separated list of hosts which are supposed to be resolved when session is offline. |  -  |  |  No  | Session Configuration |
| `"aether.offline.protocols"` | `String` | Comma-separated list of protocols which are supposed to be resolved when session is offline. |  -  |  |  No  | Session Configuration |
| `"aether.offline.repositories"` | `String` | Comma-separated list of repository IDs which are supposed to be resolved when session is offline. |  -  | 2.0.8 |  No  | Session Configuration |
| `"aether.priority.<class>"` | `Float` | The priority to use for a certain extension class. <code>&lt;class&gt;</code> can either be the fully qualified name or the simple name of a class. If the class name ends with Factory that suffix could optionally be left out. This configuration is used by <code>org.eclipse.aether.internal.impl.PrioritizedComponents</code> internal utility to sort classes by priority. This is reusable utility (so an extension can make use of it), but by default in "vanilla" Resolver following classes are sorted: <ul> <li> <code>org.eclipse.aether.spi.localrepo.LocalRepositoryManagerFactory</code> </li> <li> <code>org.eclipse.aether.spi.connector.RepositoryConnectorFactory</code> </li> <li> <code>org.eclipse.aether.spi.connector.layout.RepositoryLayoutFactory</code> </li> <li> <code>org.eclipse.aether.spi.connector.transport.TransporterFactory</code> </li> <li> <code>org.eclipse.aether.spi.artifact.decorator.ArtifactDecoratorFactory</code> </li> <li> <code>org.eclipse.aether.spi.artifact.generator.ArtifactGeneratorFactory</code> </li> <li> <code>org.eclipse.aether.impl.MetadataGeneratorFactory</code> </li> </ul> |  -  |  |  No  | Session Configuration |
| `"aether.priority.cached"` | `Boolean` | A flag indicating whether the created ordered components should be cached in session. |  `true`  | 2.0.0 |  No  | Session Configuration |
| `"aether.priority.implicit"` | `Boolean` | A flag indicating whether the priorities of pluggable extensions are implicitly given by their iteration order such that the first extension has the highest priority. If set, an extension's built-in priority as well as any corresponding <code>aether.priority.*</code> configuration properties are ignored when searching for a suitable implementation among the available extensions. This priority mode is meant for cases where the application will present/inject extensions in the desired search order. |  `false`  |  |  No  | Session Configuration |
| `"aether.remoteRepositoryFilter.groupId"` | `Boolean` | Configuration to enable the GroupId filter (enabled by default). Can be fine-tuned per repository using repository ID suffixes. <strong>Important:</strong> For this filter to take effect, you must provide configuration files. Without configuration files, the enabled filter remains dormant and does not interfere with resolution. <strong>Configuration Files:</strong> <ul> <li>Location: Directory specified by <code>#CONFIG_PROP_BASEDIR</code> (defaults to <code>$LOCAL_REPO/.remoteRepositoryFilters</code> )</li> <li>Naming: <code>groupId-$(repository.id).txt</code> </li> <li>Content: One groupId per line to allow/block from the repository</li> </ul> <strong>Recommended Setup (Per-Project):</strong> Use project-specific configuration to avoid repository ID clashes. Add to <code>.mvn/maven.config</code> : <pre> -Daether.remoteRepositoryFilter.groupId=true -Daether.remoteRepositoryFilter.groupId.basedir=${session.rootDirectory}/.mvn/rrf/ </pre> Then create <code>groupId-myrepoId.txt</code> files in the <code>.mvn/rrf/</code> directory and commit them to version control. |  `true`  | 1.9.0 |  Yes  | Session Configuration |
| `"aether.remoteRepositoryFilter.groupId.basedir"` | `String` | The basedir where to store filter files. If path is relative, it is resolved from local repository root. |  `".remoteRepositoryFilters"`  | 1.9.0 |  No  | Session Configuration |
| `"aether.remoteRepositoryFilter.groupId.noInputOutcome"` | `Boolean` | Determines what happens when the filter is enabled, but has no groupId file available for given remote repository to work with. When set to <code>true</code> (default), the filter allows all requests to proceed for given remote repository when no groupId file is available. When set to <code>false</code> , the filter blocks all requests toward given remote repository when no groupId file is available. This setting allows repoId suffix, hence, can determine "global" or "repository targeted" behaviors. |  `true`  | 2.0.14 |  Yes  | Session Configuration |
| `"aether.remoteRepositoryFilter.groupId.record"` | `Boolean` | Should filter go into "record" mode (and collect encountered artifacts)? |  `false`  | 1.9.0 |  No  | Session Configuration |
| `"aether.remoteRepositoryFilter.groupId.skipped"` | `Boolean` | Configuration to skip the GroupId filter for given request. This configuration is evaluated and if <code>true</code> the GroupId remote filter will not kick in. |  `false`  | 2.0.14 |  Yes  | Session Configuration |
| `"aether.remoteRepositoryFilter.prefixes"` | `Boolean` | Configuration to enable the Prefixes filter (enabled by default). Can be fine-tuned per repository using repository ID suffixes. <strong>Important:</strong> For this filter to take effect, configuration files must be available. Without configuration files, the enabled filter remains dormant and does not interfere with resolution. <strong>Configuration File Resolution:</strong> <ol> <li><strong>User-provided files:</strong> Checked first from directory specified by <code>#CONFIG_PROP_BASEDIR</code> (defaults to <code>$LOCAL_REPO/.remoteRepositoryFilters</code> )</li> <li><strong>Auto-discovery:</strong> If not found, attempts to download from remote repository and cache locally</li> </ol> <strong>File Naming:</strong> <code>prefixes-$(repository.id).txt</code> <strong>Recommended Setup (Auto-Discovery with Override Capability):</strong> Start with auto-discovery, but prepare for project-specific overrides. Add to <code>.mvn/maven.config</code> : <pre> -Daether.remoteRepositoryFilter.prefixes=true -Daether.remoteRepositoryFilter.prefixes.basedir=${session.rootDirectory}/.mvn/rrf/ </pre> <strong>Initial setup:</strong> Don't provide any files - rely on auto-discovery as repositories are accessed. <strong>Override when needed:</strong> Create <code>prefixes-myrepoId.txt</code> files in <code>.mvn/rrf/</code> and commit to version control. <strong>Caching:</strong> Auto-discovered prefix files are cached in the local repository. |  `true`  | 1.9.0 |  Yes  | Session Configuration |
| `"aether.remoteRepositoryFilter.prefixes.basedir"` | `String` | The basedir where to store filter files. If path is relative, it is resolved from local repository root. |  `".remoteRepositoryFilters"`  | 1.9.0 |  No  | Session Configuration |
| `"aether.remoteRepositoryFilter.prefixes.noInputOutcome"` | `Boolean` | Determines what happens when the filter is enabled, but has no prefixes available for given remote repository to work with. When set to <code>true</code> (default), the filter allows all requests to proceed for given remote repository when no prefixes are available. When set to <code>false</code> , the filter blocks all requests toward given remote repository when no prefixes are available. This setting allows repoId suffix, hence, can determine "global" or "repository targeted" behaviors. |  `true`  | 2.0.14 |  Yes  | Session Configuration |
| `"aether.remoteRepositoryFilter.prefixes.resolvePrefixFiles"` | `Boolean` | Configuration to allow Prefixes file resolution attempt from remote repository as "auto discovery". If this configuration set to <code>false</code> only user-provided prefixes will be used. |  `true`  | 2.0.14 |  Yes  | Session Configuration |
| `"aether.remoteRepositoryFilter.prefixes.skipped"` | `Boolean` | Configuration to skip the Prefixes filter for given request. This configuration is evaluated and if <code>true</code> the prefixes remote filter will not kick in. Main use case is by filter itself, to prevent recursion during discovery of remote prefixes file, but this also allows other components to control prefix filter discovery, while leaving configuration like <code>#CONFIG_PROP_ENABLED</code> still show the "real state". |  `false`  | 2.0.14 |  Yes  | Session Configuration |
| `"aether.remoteRepositoryFilter.prefixes.useMirroredRepositories"` | `Boolean` | Configuration to allow Prefixes filter to auto-discover prefixes from mirrored repositories as well. For this to work <em>Maven should be aware</em> that given remote repository is mirror and is usually backed by MRM. Given multiple MRM implementations messes up prefixes file, is better to just skip these. In other case, one may use <code>#CONFIG_PROP_ENABLED</code> with repository ID suffix. |  `false`  | 2.0.14 |  Yes  | Session Configuration |
| `"aether.remoteRepositoryFilter.prefixes.useRepositoryManagers"` | `Boolean` | Configuration to allow Prefixes filter to auto-discover prefixes from repository managers as well. For this to work <em>Maven should be aware</em> that given remote repository is backed by repository manager. Given multiple MRM implementations messes up prefixes file, is better to just skip these. In other case, one may use <code>#CONFIG_PROP_ENABLED</code> with repository ID suffix. <em>Note: as of today, nothing sets this on remote repositories, but is added for future.</em> |  `false`  | 2.0.14 |  Yes  | Session Configuration |
| `"aether.remoteRepositoryFilter.repositoryKeyFunction"` | `String` | <b>Experimental:</b> Configuration for "repository key" function. Note: repository key functions other than "nid" produce repository keys will be <em>way different that those produced with previous versions or without this option enabled</em>. Filter uses this key function to lay down and look up files to use in filtering. |  `"nid"`  | 2.0.14 |  No  | Session Configuration |
| `"aether.snapshotFilter"` | `Boolean` | The key in the repository session's <code>RepositorySystemSession#getConfigProperties() configurationproperties</code> used to store a <code>Boolean</code> flag whether this filter should be forced to ban snapshots. By default, snapshots are only filtered if the root artifact is not a snapshot. |  `false`  |  |  No  | Session Configuration |
| `"aether.syncContext.named.basedir.locksDir"` | `String` | The location of the directory toi use for locks. If relative path, it is resolved from the local repository root. |  `".locks"`  | 1.9.0 |  No  | Session Configuration |
| `"aether.syncContext.named.discriminating.discriminator"` | `String` | Configuration property to pass in discriminator, if needed. If not present, it is auto-calculated. |  -  | 1.7.0 |  No  | Session Configuration |
| `"aether.syncContext.named.discriminating.hostname"` | `String` | Configuration property to pass in hostname, if needed. If not present, hostname as reported by system will be used. |  -  | 1.7.0 |  No  | Session Configuration |
| `"aether.syncContext.named.factory"` | `String` | Name of the lock factory to use in session. Out of the box supported ones are "file-lock", "rwlock-local", "semaphore-local", "noop". By adding extensions one can extend available lock factories (for example IPC locking). |  `"file-lock"`  | 1.9.1 |  No  | Session Configuration |
| `"aether.syncContext.named.hashing.depth"` | `Integer` | The depth how many levels should adapter create. Acceptable values are 0-4 (inclusive). |  `2`  | 1.9.0 |  No  | Session Configuration |
| `"aether.syncContext.named.nameMapper"` | `String` | Name of the name mapper to use in session. Out of the box supported ones are "static", "gav", "gaecv", "file-gav", "file-gaecv", "file-hgav", "file-hgaecv", "file-static" and "discriminating". |  `"file-gaecv"`  | 1.9.1 |  No  | Session Configuration |
| `"aether.syncContext.named.redisson.address"` | `String` | Address of the Redis instance. Optional. |  `"redis://localhost:6379"`  | 2.0.0 |  No  | Java System Properties |
| `"aether.syncContext.named.redisson.configFile"` | `String` | Path to a Redisson configuration file in YAML format. Read official documentation for details. |  -  | 1.7.0 |  No  | Java System Properties |
| `"aether.syncContext.named.retry"` | `Integer` | The amount of retries on time-out. |  `1`  | 1.7.0 |  No  | Session Configuration |
| `"aether.syncContext.named.retry.wait"` | `Long` | The amount of milliseconds to wait between retries on time-out. |  `200l`  | 1.7.0 |  No  | Session Configuration |
| `"aether.syncContext.named.time"` | `Long` | The maximum of time amount to be blocked to obtain lock. |  `900l`  | 1.7.0 |  No  | Session Configuration |
| `"aether.syncContext.named.time.unit"` | `String` | The unit of maximum time amount to be blocked to obtain lock. Use TimeUnit enum names. |  `"SECONDS"`  | 1.7.0 |  No  | Session Configuration |
| `"aether.system.dependencyVisitor"` | `String` | A flag indicating which visitor should be used to "flatten" the dependency graph into list. In Maven 4 the default is new "levelOrder", while Maven 3 used "preOrder". This property accepts values "preOrder", "postOrder" and "levelOrder". |  `"levelOrder"`  | 2.0.0 |  No  | Session Configuration |
| `"aether.system.repositoryKeyFunction"` | `String` | <b>Experimental:</b> Configuration for system-wide "repository key" function. Accepted and recommended values: "nid" (default), "nid_hurl" and "ngurk", while "simple" is Maven 3 legacy, technically equivalent to "nid". For complete description see enum <code>org.eclipse.aether.util.repository.RepositoryIdHelper.RepositoryKeyType</code> in utils. <em>Warning:</em> repository key function affects Resolver fundamentally and may have unexpected results! Only change this if you know what you are doing! |  `"nid"`  | 2.0.14 |  No  | Session Configuration |
| `"aether.transport.apache.followRedirects"` | `Boolean` | If enabled, Apache HttpClient will follow HTTP redirects. |  `true`  | 2.0.2 |  Yes  | Session Configuration |
| `"aether.transport.apache.https.cipherSuites"` | `String` | Comma-separated list of <a href="https://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#ciphersuites">Cipher Suites</a> which are enabled for HTTPS connections. |  -  | 2.0.0 |  No  | Session Configuration |
| `"aether.transport.apache.https.protocols"` | `String` | Comma-separated list of <a href="https://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#jssenames">Protocols </a> which are enabled for HTTPS connections. |  -  | 2.0.0 |  No  | Session Configuration |
| `"aether.transport.apache.maxRedirects"` | `Integer` | The max redirect count to follow. |  `5`  | 2.0.2 |  Yes  | Session Configuration |
| `"aether.transport.apache.retryHandler.name"` | `String` | The name of retryHandler, supported values are “standard”, that obeys RFC-2616, regarding idempotent methods, and “default” that considers requests w/o payload as idempotent. |  `"standard"`  | 2.0.0 |  Yes  | Session Configuration |
| `"aether.transport.apache.retryHandler.requestSentEnabled"` | `Boolean` | Set to true if it is acceptable to retry non-idempotent requests, that have been sent. |  `false`  | 2.0.0 |  Yes  | Session Configuration |
| `"aether.transport.apache.useSystemProperties"` | `Boolean` | If enabled, underlying Apache HttpClient will use system properties as well to configure itself (typically used to set up HTTP Proxy via Java system properties). See HttpClientBuilder for used properties. This mode is not recommended, better use documented ways of configuration instead. |  `false`  | 2.0.0 |  Yes  | Session Configuration |
| `"aether.transport.classpath.loader"` | `ClassLoader` | The key in the repository session's <code>RepositorySystemSession#getConfigProperties() configurationproperties</code> used to store a <code>ClassLoader</code> from which resources should be retrieved. If unspecified, the <code>Thread#getContextClassLoader() context class loader</code> of the current thread will be used. |  -  |  |  No  | Session Configuration |
| `"aether.transport.http.connectTimeout"` | `Integer` | The maximum amount of time (in milliseconds) to wait for a successful connection to a remote server. Non-positive values indicate no timeout. |  `30000`  |  |  Yes  | Session Configuration |
| `"aether.transport.http.connectionMaxTtl"` | `Integer` | Total time to live in seconds for an HTTP connection, after that time, the connection will be dropped (no matter for how long it was idle). |  `300`  | 1.9.8 |  Yes  | Session Configuration |
| `"aether.transport.http.credentialEncoding"` | `String` | The encoding/charset to use when exchanging credentials with HTTP servers. Besides this general key, clients may also specify the encoding for a specific remote repository by appending the suffix <code>.&lt;repoId&gt;</code> to this key when storing the charset name. |  `"ISO-8859-1"`  |  |  Yes  | Session Configuration |
| `"aether.transport.http.expectContinue"` | `Boolean` | Boolean flag should the HTTP transport use expect-continue handshake for PUT requests. Not all transport support this option. This option may be needed for some broken HTTP servers. Default value corresponds to given transport default one (resolver does not override those), but if configuration IS given, it will replace given transport own default value. |  -  | 1.9.17 |  Yes  | Session Configuration |
| `"aether.transport.http.headers"` | `java.util.Map` | The request headers to use for HTTP-based repository connectors. The headers are specified using a <code>Map<String, String></code> , mapping a header name to its value. Besides this general key, clients may also specify headers for a specific remote repository by appending the suffix <code>.&lt;repoId&gt;</code> to this key when storing the headers map. The repository-specific headers map is supposed to be complete, i.e. is not merged with the general headers map. |  -  |  |  Yes  | Session Configuration |
| `"aether.transport.http.localAddress"` | `String` | The local address (interface) to use with HTTP transport. Not all transport supports this option. |  -  | 2.0.0 |  Yes  | Session Configuration |
| `"aether.transport.http.maxConnectionsPerRoute"` | `Integer` | The maximum concurrent connections per route HTTP client is allowed to use. |  `50`  | 1.9.8 |  Yes  | Session Configuration |
| `"aether.transport.http.preemptiveAuth"` | `Boolean` | Should HTTP client use preemptive-authentication for all HTTP verbs (works only w/ BASIC). By default, is disabled, as it is considered less secure. |  `false`  | 1.9.6 |  Yes  | Session Configuration |
| `"aether.transport.http.preemptivePutAuth"` | `Boolean` | Boolean flag should the HTTP transport use preemptive-auth for PUT requests. Not all transport support this option. |  `true`  | 2.0.0 (moved out from maven-resolver-transport-http). |  Yes  | Session Configuration |
| `"aether.transport.http.requestTimeout"` | `Integer` | The maximum amount of time (in milliseconds) to wait for remaining data to arrive from a remote server. Note that this timeout does not restrict the overall duration of a request, it only restricts the duration of inactivity between consecutive data packets. Non-positive values indicate no timeout. |  `1800000`  |  |  Yes  | Session Configuration |
| `"aether.transport.http.retryHandler.count"` | `Integer` | The maximum number of times a request to a remote server should be retried in case of an error. |  `3`  | 1.9.6 |  Yes  | Session Configuration |
| `"aether.transport.http.retryHandler.interval"` | `Long` | The initial retry interval in millis of request to a remote server should be waited in case of "too many requests" (HTTP codes 429 and 503). Accepts long as milliseconds. This value is used if remote server does not use <code>Retry-After</code> header, in which case Server value is obeyed. |  `5000l`  | 1.9.16 |  Yes  | Session Configuration |
| `"aether.transport.http.retryHandler.intervalMax"` | `Long` | The maximum retry interval in millis of request to a remote server above which the request should be aborted instead. In theory, a malicious server could tell Maven "come back after 100 years" that would stall the build for some. Using this parameter Maven will fail the request instead, if interval is above this value. |  `300000l`  | 1.9.16 |  Yes  | Session Configuration |
| `"aether.transport.http.retryHandler.serviceUnavailable"` | `String` | The HTTP codes of remote server responses that should be handled as "too many requests" (examples: HTTP codes 429 and 503). Accepts comma separated list of HTTP response codes. |  `"429,503"`  | 1.9.16 |  Yes  | Session Configuration |
| `"aether.transport.http.reuseConnections"` | `Boolean` | Should HTTP client reuse connections (in other words, pool connections) or not? |  `true`  | 1.9.8 |  Yes  | Session Configuration |
| `"aether.transport.http.supportWebDav"` | `Boolean` | Boolean flag should the HTTP transport support WebDAV remote. Not all transport support this option. |  `false`  | 2.0.0 (moved out from maven-resolver-transport-http). |  Yes  | Session Configuration |
| `"aether.transport.http.userAgent"` | `String` | The user agent that repository connectors should report to servers. |  `"Aether"`  |  |  No  | Session Configuration |
| `"aether.transport.https.securityMode"` | `String` | The mode that sets HTTPS transport "security mode": to ignore any SSL errors (certificate validity checks, hostname verification). The default value is <code>#HTTPS_SECURITY_MODE_DEFAULT</code> . |  `"default"`  | 1.9.6 |  Yes  | Session Configuration |
| `"aether.transport.jdk.httpVersion"` | `String` | Use string representation of HttpClient version enum "HTTP_2" or "HTTP_1_1" to set default HTTP protocol to use. |  `"HTTP_1_1"`  | 2.0.0 |  Yes  | Session Configuration |
| `"aether.transport.jdk.maxConcurrentRequests"` | `Integer` | The hard limit of maximum concurrent requests JDK transport can do. This is a workaround for the fact, that in HTTP/2 mode, JDK HttpClient initializes this value to Integer.MAX_VALUE (!) and lowers it on first response from the remote server (but it may be too late). See JDK bug <a href="https://bugs.openjdk.org/browse/JDK-8225647">JDK-8225647</a> for details. |  `100`  | 2.0.0 |  Yes  | Session Configuration |
| `"aether.transport.jetty.followRedirects"` | `Boolean` | If enabled, Jetty client will follow HTTP redirects. |  `true`  | 2.0.1 |  Yes  | Session Configuration |
| `"aether.transport.jetty.maxRedirects"` | `Integer` | The max redirect count to follow. |  `5`  | 2.0.1 |  Yes  | Session Configuration |
| `"aether.transport.minio.fixedBucketName"` | `String` | The fixed bucket name to use. |  `"maven"`  | 2.0.2 |  Yes  | Session Configuration |
| `"aether.transport.minio.objectNameMapper"` | `String` | Object name mapper to use. |  `"fixedBucket"`  | 2.0.2 |  Yes  | Session Configuration |
| `"aether.transport.wagon.config"` | `Object` | The configuration to use for the Wagon provider. |  -  |  |  Yes  | Session Configuration |
| `"aether.transport.wagon.perms.dirMode"` | `String` | Octal numerical notation of permissions to set for newly created directories. Only considered by certain Wagon providers. |  -  |  |  Yes  | Session Configuration |
| `"aether.transport.wagon.perms.fileMode"` | `String` | Octal numerical notation of permissions to set for newly created files. Only considered by certain Wagon providers. |  -  |  |  Yes  | Session Configuration |
| `"aether.transport.wagon.perms.group"` | `String` | Group which should own newly created directories/files. Only considered by certain Wagon providers. |  -  |  |  Yes  | Session Configuration |
| `"aether.trustedChecksumsSource.repositoryKeyFunction"` | `String` | <b>Experimental:</b> Configuration for "repository key" function. Note: repository key functions other than "nid" produce repository keys will be <em>way different that those produced with previous versions or without this option enabled</em>. Checksum source uses this key function to lay down and look up files to use in sources. |  `"nid"`  | 2.0.14 |  No  | Session Configuration |
| `"aether.trustedChecksumsSource.sparseDirectory"` | `Boolean` | Is checksum source enabled? |  `false`  | 1.9.0 |  No  | Session Configuration |
| `"aether.trustedChecksumsSource.sparseDirectory.basedir"` | `String` | The basedir where checksums are. If relative, is resolved from local repository root. |  `".checksums"`  | 1.9.0 |  No  | Session Configuration |
| `"aether.trustedChecksumsSource.sparseDirectory.originAware"` | `Boolean` | Is source origin aware? |  `true`  | 1.9.0 |  No  | Session Configuration |
| `"aether.trustedChecksumsSource.summaryFile"` | `Boolean` | Is checksum source enabled? |  `false`  | 1.9.0 |  No  | Session Configuration |
| `"aether.trustedChecksumsSource.summaryFile.basedir"` | `String` | The basedir where checksums are. If relative, is resolved from local repository root. |  `".checksums"`  | 1.9.0 |  No  | Session Configuration |
| `"aether.trustedChecksumsSource.summaryFile.originAware"` | `Boolean` | Is source origin aware? |  `true`  | 1.9.0 |  No  | Session Configuration |
| `"aether.updateCheckManager.sessionState"` | `String` | Manages the session state, i.e. influences if the same download requests to artifacts/metadata will happen multiple times within the same RepositorySystemSession. If "enabled" will enable the session state. If "bypass" will enable bypassing (i.e. store all artifact ids/metadata ids which have been updates but not evaluating those). All other values lead to disabling the session state completely. |  `"enabled"`  |  |  No  | Session Configuration |
| `"aether.util.versionScheme.cacheDebug"` | `Boolean` | A flag indicating whether version scheme cache statistics should be printed on JVM shutdown. This is useful for analyzing cache performance and effectiveness in development and testing scenarios. |  `false`  | 2.0.10 |  No  | Session Configuration |


All properties which have `yes` in the column `Supports Repo ID Suffix` can be optionally configured specifically for a repository id. In that case the configuration property needs to be suffixed with a period followed by the repository id of the repository to configure, e.g. `aether.connector.http.headers.central` for repository with id `central`.

## Property Type Conversion

If the value is not given in the target type the following conversions are applied.

From | To | With
--- | --- | ---
`String` | `boolean` | [`Boolean.parseBoolean(...)`](https://docs.oracle.com/javase/7/docs/api/java/lang/Boolean.html#parseBoolean(java.lang.String))
`String` | `int` | [`Integer.parseInt(...)`](https://docs.oracle.com/javase/7/docs/api/java/lang/Integer.html#parseInt(java.lang.String))
`String` | `long` | [`Long.parseLong(...)`](https://docs.oracle.com/javase/7/docs/api/java/lang/Long.html#parseLong(java.lang.String))
`String` | `float` | [`Float.parseFloat(...)`](https://docs.oracle.com/javase/7/docs/api/java/lang/Float.html#parseFloat(java.lang.String))

## Set Configuration from Apache Maven

To set one of the configuration options from above just use system variables. As system variables only support String values the type conversion mentioned above needs to be leveraged.
Sometimes Maven uses different default values than the Maven Resolver itself or tries to extract certain values from the `settings.xml`. For details refer to [`DefaultRepositorySystemSessionFactory`](https://github.com/apache/maven/blob/master/impl/maven-core/src/main/java/org/apache/maven/internal/aether/DefaultRepositorySystemSessionFactory.java).

