/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements. See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache license, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License. You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the license for the specific language governing permissions and
   * limitations under the license.
   */
  package org.apache.logging.log4j.core.tools.picocli;
  
  import java.io.File;
  import java.io.PrintStream;
  import java.lang.annotation.ElementType;
  import java.lang.annotation.Retention;
  import java.lang.annotation.RetentionPolicy;
  import java.lang.annotation.Target;
  import java.lang.reflect.Array;
  import java.lang.reflect.Constructor;
  import java.lang.reflect.Field;
  import java.lang.reflect.ParameterizedType;
  import java.lang.reflect.Type;
  import java.lang.reflect.WildcardType;
  import java.math.BigDecimal;
  import java.math.BigInteger;
  import java.net.InetAddress;
  import java.net.MalformedURLException;
  import java.net.URI;
  import java.net.URISyntaxException;
  import java.net.URL;
  import java.nio.charset.Charset;
  import java.nio.file.Path;
  import java.nio.file.Paths;
  import java.sql.Time;
  import java.text.BreakIterator;
  import java.text.ParseException;
  import java.text.SimpleDateFormat;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.Date;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.LinkedHashMap;
  import java.util.LinkedHashSet;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Map;
  import java.util.Queue;
  import java.util.Set;
  import java.util.SortedSet;
  import java.util.Stack;
  import java.util.TreeSet;
  import java.util.UUID;
  import java.util.concurrent.Callable;
  import java.util.regex.Pattern;
  
  import org.apache.logging.log4j.core.tools.picocli.CommandLine.Help.Ansi.IStyle;
  import org.apache.logging.log4j.core.tools.picocli.CommandLine.Help.Ansi.Style;
  import org.apache.logging.log4j.core.tools.picocli.CommandLine.Help.Ansi.Text;
  
  import static java.util.Locale.ENGLISH;
  import static org.apache.logging.log4j.core.tools.picocli.CommandLine.Help.Column.Overflow.SPAN;
  import static org.apache.logging.log4j.core.tools.picocli.CommandLine.Help.Column.Overflow.TRUNCATE;
  import static org.apache.logging.log4j.core.tools.picocli.CommandLine.Help.Column.Overflow.WRAP;
  
  /**
   * <p>
   * CommandLine interpreter that uses reflection to initialize an annotated domain object with values obtained from the
   * command line arguments.
   * </p><h2>Example</h2>
   * <pre>import static picocli.CommandLine.*;
   *
   * &#064;Command(header = "Encrypt FILE(s), or standard input, to standard output or to the output file.",
   *          version = "v1.2.3")
   * public class Encrypt {
   *
   *     &#064;Parameters(type = File.class, description = "Any number of input files")
   *     private List&lt;File&gt; files = new ArrayList&lt;File&gt;();
   *
   *     &#064;Option(names = { "-o", "--out" }, description = "Output file (default: print to console)")
   *     private File outputFile;
   *
   *     &#064;Option(names = { "-v", "--verbose"}, description = "Verbosely list files processed")
   *     private boolean verbose;
   *
   *     &#064;Option(names = { "-h", "--help", "-?", "-help"}, usageHelp = true, description = "Display this help and exit")
   *     private boolean help;
   *
   *     &#064;Option(names = { "-V", "--version"}, versionHelp = true, description = "Display version info and exit")
  *     private boolean versionHelp;
  * }
  * </pre>
  * <p>
  * Use {@code CommandLine} to initialize a domain object as follows:
  * </p><pre>
  * public static void main(String... args) {
  *     Encrypt encrypt = new Encrypt();
  *     try {
  *         List&lt;CommandLine&gt; parsedCommands = new CommandLine(encrypt).parse(args);
  *         if (!CommandLine.printHelpIfRequested(parsedCommands, System.err, Help.Ansi.AUTO)) {
  *             runProgram(encrypt);
  *         }
  *     } catch (ParameterException ex) { // command line arguments could not be parsed
  *         System.err.println(ex.getMessage());
  *         ex.getCommandLine().usage(System.err);
  *     }
  * }
  * </pre><p>
  * Invoke the above program with some command line arguments. The below are all equivalent:
  * </p>
  * <pre>
  * --verbose --out=outfile in1 in2
  * --verbose --out outfile in1 in2
  * -v --out=outfile in1 in2
  * -v -o outfile in1 in2
  * -v -o=outfile in1 in2
  * -vo outfile in1 in2
  * -vo=outfile in1 in2
  * -v -ooutfile in1 in2
  * -vooutfile in1 in2
  * </pre>
  */
 public class CommandLine {
     /** This is picocli version {@value}. */
     public static final String VERSION = "2.0.3";
 
     private final Tracer tracer = new Tracer();
     private final Interpreter interpreter;
     private String commandName = Help.DEFAULT_COMMAND_NAME;
     private boolean overwrittenOptionsAllowed = false;
     private boolean unmatchedArgumentsAllowed = false;
     private List<String> unmatchedArguments = new ArrayList<String>();
     private CommandLine parent;
     private boolean usageHelpRequested;
     private boolean versionHelpRequested;
     private List<String> versionLines = new ArrayList<String>();
 
     /**
      * Constructs a new {@code CommandLine} interpreter with the specified annotated object.
      * When the {@link #parse(String...)} method is called, fields of the specified object that are annotated
      * with {@code @Option} or {@code @Parameters} will be initialized based on command line arguments.
      * @param command the object to initialize from the command line arguments
      * @throws InitializationException if the specified command object does not have a {@link Command}, {@link Option} or {@link Parameters} annotation
      */
     public CommandLine(Object command) {
         interpreter = new Interpreter(command);
     }
 
     /** Registers a subcommand with the specified name. For example:
      * <pre>
      * CommandLine commandLine = new CommandLine(new Git())
      *         .addSubcommand("status",   new GitStatus())
      *         .addSubcommand("commit",   new GitCommit();
      *         .addSubcommand("add",      new GitAdd())
      *         .addSubcommand("branch",   new GitBranch())
      *         .addSubcommand("checkout", new GitCheckout())
      *         //...
      *         ;
      * </pre>
      *
      * <p>The specified object can be an annotated object or a
      * {@code CommandLine} instance with its own nested subcommands. For example:</p>
      * <pre>
      * CommandLine commandLine = new CommandLine(new MainCommand())
      *         .addSubcommand("cmd1",                 new ChildCommand1()) // subcommand
      *         .addSubcommand("cmd2",                 new ChildCommand2())
      *         .addSubcommand("cmd3", new CommandLine(new ChildCommand3()) // subcommand with nested sub-subcommands
      *                 .addSubcommand("cmd3sub1",                 new GrandChild3Command1())
      *                 .addSubcommand("cmd3sub2",                 new GrandChild3Command2())
      *                 .addSubcommand("cmd3sub3", new CommandLine(new GrandChild3Command3()) // deeper nesting
      *                         .addSubcommand("cmd3sub3sub1", new GreatGrandChild3Command3_1())
      *                         .addSubcommand("cmd3sub3sub2", new GreatGrandChild3Command3_2())
      *                 )
      *         );
      * </pre>
      * <p>The default type converters are available on all subcommands and nested sub-subcommands, but custom type
      * converters are registered only with the subcommand hierarchy as it existed when the custom type was registered.
      * To ensure a custom type converter is available to all subcommands, register the type converter last, after
      * adding subcommands.</p>
      * <p>See also the {@link Command#subcommands()} annotation to register subcommands declaratively.</p>
      *
      * @param name the string to recognize on the command line as a subcommand
      * @param command the object to initialize with command line arguments following the subcommand name.
      *          This may be a {@code CommandLine} instance with its own (nested) subcommands
      * @return this CommandLine object, to allow method chaining
      * @see #registerConverter(Class, ITypeConverter)
      * @since 0.9.7
      * @see Command#subcommands()
      */
     public CommandLine addSubcommand(String name, Object command) {
         CommandLine commandLine = toCommandLine(command);
         commandLine.parent = this;
         interpreter.commands.put(name, commandLine);
         return this;
     }
     /** Returns a map with the subcommands {@linkplain #addSubcommand(String, Object) registered} on this instance.
      * @return a map with the registered subcommands
      * @since 0.9.7
      */
     public Map<String, CommandLine> getSubcommands() {
         return new LinkedHashMap<String, CommandLine>(interpreter.commands);
     }
     /**
      * Returns the command that this is a subcommand of, or {@code null} if this is a top-level command.
      * @return the command that this is a subcommand of, or {@code null} if this is a top-level command
      * @see #addSubcommand(String, Object)
      * @see Command#subcommands()
      * @since 0.9.8
      */
     public CommandLine getParent() {
         return parent;
     }
 
     /** Returns the annotated object that this {@code CommandLine} instance was constructed with.
      * @param <T> the type of the variable that the return value is being assigned to
      * @return the annotated object that this {@code CommandLine} instance was constructed with
      * @since 0.9.7
      */
     public <T> T getCommand() {
         return (T) interpreter.command;
     }
 
     /** Returns {@code true} if an option annotated with {@link Option#usageHelp()} was specified on the command line.
      * @return whether the parser encountered an option annotated with {@link Option#usageHelp()}.
      * @since 0.9.8 */
     public boolean isUsageHelpRequested() { return usageHelpRequested; }
 
     /** Returns {@code true} if an option annotated with {@link Option#versionHelp()} was specified on the command line.
      * @return whether the parser encountered an option annotated with {@link Option#versionHelp()}.
      * @since 0.9.8 */
     public boolean isVersionHelpRequested() { return versionHelpRequested; }
 
     /** Returns whether options for single-value fields can be specified multiple times on the command line.
      * The default is {@code false} and a {@link OverwrittenOptionException} is thrown if this happens.
      * When {@code true}, the last specified value is retained.
      * @return {@code true} if options for single-value fields can be specified multiple times on the command line, {@code false} otherwise
      * @since 0.9.7
      */
     public boolean isOverwrittenOptionsAllowed() {
         return overwrittenOptionsAllowed;
     }
 
     /** Sets whether options for single-value fields can be specified multiple times on the command line without a {@link OverwrittenOptionException} being thrown.
      * <p>The specified setting will be registered with this {@code CommandLine} and the full hierarchy of its
      * subcommands and nested sub-subcommands <em>at the moment this method is called</em>. Subcommands added
      * later will have the default setting. To ensure a setting is applied to all
      * subcommands, call the setter last, after adding subcommands.</p>
      * @param newValue the new setting
      * @return this {@code CommandLine} object, to allow method chaining
      * @since 0.9.7
      */
     public CommandLine setOverwrittenOptionsAllowed(boolean newValue) {
         this.overwrittenOptionsAllowed = newValue;
         for (CommandLine command : interpreter.commands.values()) {
             command.setOverwrittenOptionsAllowed(newValue);
         }
         return this;
     }
 
     /** Returns whether the end user may specify arguments on the command line that are not matched to any option or parameter fields.
      * The default is {@code false} and a {@link UnmatchedArgumentException} is thrown if this happens.
      * When {@code true}, the last unmatched arguments are available via the {@link #getUnmatchedArguments()} method.
      * @return {@code true} if the end use may specify unmatched arguments on the command line, {@code false} otherwise
      * @see #getUnmatchedArguments()
      * @since 0.9.7
      */
     public boolean isUnmatchedArgumentsAllowed() {
         return unmatchedArgumentsAllowed;
     }
 
     /** Sets whether the end user may specify unmatched arguments on the command line without a {@link UnmatchedArgumentException} being thrown.
      * <p>The specified setting will be registered with this {@code CommandLine} and the full hierarchy of its
      * subcommands and nested sub-subcommands <em>at the moment this method is called</em>. Subcommands added
      * later will have the default setting. To ensure a setting is applied to all
      * subcommands, call the setter last, after adding subcommands.</p>
      * @param newValue the new setting. When {@code true}, the last unmatched arguments are available via the {@link #getUnmatchedArguments()} method.
      * @return this {@code CommandLine} object, to allow method chaining
      * @since 0.9.7
      * @see #getUnmatchedArguments()
      */
     public CommandLine setUnmatchedArgumentsAllowed(boolean newValue) {
         this.unmatchedArgumentsAllowed = newValue;
         for (CommandLine command : interpreter.commands.values()) {
             command.setUnmatchedArgumentsAllowed(newValue);
         }
         return this;
     }
 
     /** Returns the list of unmatched command line arguments, if any.
      * @return the list of unmatched command line arguments or an empty list
      * @see #isUnmatchedArgumentsAllowed()
      * @since 0.9.7
      */
     public List<String> getUnmatchedArguments() {
         return unmatchedArguments;
     }
 
     /**
      * <p>
      * Convenience method that initializes the specified annotated object from the specified command line arguments.
      * </p><p>
      * This is equivalent to
      * </p><pre>
      * CommandLine cli = new CommandLine(command);
      * cli.parse(args);
      * return command;
      * </pre>
      *
      * @param command the object to initialize. This object contains fields annotated with
      *          {@code @Option} or {@code @Parameters}.
      * @param args the command line arguments to parse
      * @param <T> the type of the annotated object
      * @return the specified annotated object
      * @throws InitializationException if the specified command object does not have a {@link Command}, {@link Option} or {@link Parameters} annotation
      * @throws ParameterException if the specified command line arguments are invalid
      * @since 0.9.7
      */
     public static <T> T populateCommand(T command, String... args) {
         CommandLine cli = toCommandLine(command);
         cli.parse(args);
         return command;
     }
 
     /** Parses the specified command line arguments and returns a list of {@code CommandLine} objects representing the
      * top-level command and any subcommands (if any) that were recognized and initialized during the parsing process.
      * <p>
      * If parsing succeeds, the first element in the returned list is always {@code this CommandLine} object. The
      * returned list may contain more elements if subcommands were {@linkplain #addSubcommand(String, Object) registered}
      * and these subcommands were initialized by matching command line arguments. If parsing fails, a
      * {@link ParameterException} is thrown.
      * </p>
      *
      * @param args the command line arguments to parse
      * @return a list with the top-level command and any subcommands initialized by this method
      * @throws ParameterException if the specified command line arguments are invalid; use
      *      {@link ParameterException#getCommandLine()} to get the command or subcommand whose user input was invalid
      */
     public List<CommandLine> parse(String... args) {
         return interpreter.parse(args);
     }
     /**
      * Represents a function that can process a List of {@code CommandLine} objects resulting from successfully
      * {@linkplain #parse(String...) parsing} the command line arguments. This is a
      * <a href="https://docs.oracle.com/javase/8/docs/api/java/util/function/package-summary.html">functional interface</a>
      * whose functional method is {@link #handleParseResult(List, PrintStream, CommandLine.Help.Ansi)}.
      * <p>
      * Implementations of this functions can be passed to the {@link #parseWithHandlers(IParseResultHandler, PrintStream, Help.Ansi, IExceptionHandler, String...) CommandLine::parseWithHandler}
      * methods to take some next step after the command line was successfully parsed.
      * </p>
      * @see RunFirst
      * @see RunLast
      * @see RunAll
      * @since 2.0 */
     public static interface IParseResultHandler {
         /** Processes a List of {@code CommandLine} objects resulting from successfully
          * {@linkplain #parse(String...) parsing} the command line arguments and optionally returns a list of results.
          * @param parsedCommands the {@code CommandLine} objects that resulted from successfully parsing the command line arguments
          * @param out the {@code PrintStream} to print help to if requested
          * @param ansi for printing help messages using ANSI styles and colors
          * @return a list of results, or an empty list if there are no results
          * @throws ExecutionException if a problem occurred while processing the parse results; use
          *      {@link ExecutionException#getCommandLine()} to get the command or subcommand where processing failed
          */
         List<Object> handleParseResult(List<CommandLine> parsedCommands, PrintStream out, Help.Ansi ansi) throws ExecutionException;
     }
     /**
      * Represents a function that can handle a {@code ParameterException} that occurred while
      * {@linkplain #parse(String...) parsing} the command line arguments. This is a
      * <a href="https://docs.oracle.com/javase/8/docs/api/java/util/function/package-summary.html">functional interface</a>
      * whose functional method is {@link #handleException(CommandLine.ParameterException, PrintStream, CommandLine.Help.Ansi, String...)}.
      * <p>
      * Implementations of this functions can be passed to the {@link #parseWithHandlers(IParseResultHandler, PrintStream, Help.Ansi, IExceptionHandler, String...) CommandLine::parseWithHandler}
      * methods to handle situations when the command line could not be parsed.
      * </p>
      * @see DefaultExceptionHandler
      * @since 2.0 */
     public static interface IExceptionHandler {
         /** Handles a {@code ParameterException} that occurred while {@linkplain #parse(String...) parsing} the command
          * line arguments and optionally returns a list of results.
          * @param ex the ParameterException describing the problem that occurred while parsing the command line arguments,
          *           and the CommandLine representing the command or subcommand whose input was invalid
          * @param out the {@code PrintStream} to print help to if requested
          * @param ansi for printing help messages using ANSI styles and colors
          * @param args the command line arguments that could not be parsed
          * @return a list of results, or an empty list if there are no results
          */
         List<Object> handleException(ParameterException ex, PrintStream out, Help.Ansi ansi, String... args);
     }
     /**
      * Default exception handler that prints the exception message to the specified {@code PrintStream}, followed by the
      * usage message for the command or subcommand whose input was invalid.
      * <p>Implementation roughly looks like this:</p>
      * <pre>
      *     System.err.println(paramException.getMessage());
      *     paramException.getCommandLine().usage(System.err);
      * </pre>
      * @since 2.0 */
     public static class DefaultExceptionHandler implements IExceptionHandler {
         @Override
         public List<Object> handleException(ParameterException ex, PrintStream out, Help.Ansi ansi, String... args) {
             out.println(ex.getMessage());
             ex.getCommandLine().usage(out, ansi);
             return Collections.emptyList();
         }
     }
     /**
      * Helper method that may be useful when processing the list of {@code CommandLine} objects that result from successfully
      * {@linkplain #parse(String...) parsing} command line arguments. This method prints out
      * {@linkplain #usage(PrintStream, Help.Ansi) usage help} if {@linkplain #isUsageHelpRequested() requested}
      * or {@linkplain #printVersionHelp(PrintStream, Help.Ansi) version help} if {@linkplain #isVersionHelpRequested() requested}
      * and returns {@code true}. Otherwise, if none of the specified {@code CommandLine} objects have help requested,
      * this method returns {@code false}.
      * <p>
      * Note that this method <em>only</em> looks at the {@link Option#usageHelp() usageHelp} and
      * {@link Option#versionHelp() versionHelp} attributes. The {@link Option#help() help} attribute is ignored.
      * </p>
      * @param parsedCommands the list of {@code CommandLine} objects to check if help was requested
      * @param out the {@code PrintStream} to print help to if requested
      * @param ansi for printing help messages using ANSI styles and colors
      * @return {@code true} if help was printed, {@code false} otherwise
      * @since 2.0 */
     public static boolean printHelpIfRequested(List<CommandLine> parsedCommands, PrintStream out, Help.Ansi ansi) {
         for (CommandLine parsed : parsedCommands) {
             if (parsed.isUsageHelpRequested()) {
                 parsed.usage(out, ansi);
                 return true;
             } else if (parsed.isVersionHelpRequested()) {
                 parsed.printVersionHelp(out, ansi);
                 return true;
             }
         }
         return false;
     }
     private static Object execute(CommandLine parsed) {
         Object command = parsed.getCommand();
         if (command instanceof Runnable) {
             try {
                 ((Runnable) command).run();
                 return null;
             } catch (Exception ex) {
                 throw new ExecutionException(parsed, "Error while running command (" + command + ")", ex);
             }
         } else if (command instanceof Callable) {
             try {
                 return ((Callable<Object>) command).call();
             } catch (Exception ex) {
                 throw new ExecutionException(parsed, "Error while calling command (" + command + ")", ex);
             }
         }
         throw new ExecutionException(parsed, "Parsed command (" + command + ") is not Runnable or Callable");
     }
     /**
      * Command line parse result handler that prints help if requested, and otherwise executes the top-level
      * {@code Runnable} or {@code Callable} command.
      * For use in the {@link #parseWithHandlers(IParseResultHandler, PrintStream, Help.Ansi, IExceptionHandler, String...) parseWithHandler} methods.
      * <p>
      * From picocli v2.0, {@code RunFirst} is used to implement the {@link #run(Runnable, PrintStream, Help.Ansi, String...) run}
      * and {@link #call(Callable, PrintStream, Help.Ansi, String...) call} convenience methods.
      * </p>
      * @since 2.0 */
     public static class RunFirst implements IParseResultHandler {
         /** Prints help if requested, and otherwise executes the top-level {@code Runnable} or {@code Callable} command.
          * If the top-level command does not implement either {@code Runnable} or {@code Callable}, a {@code ExecutionException}
          * is thrown detailing the problem and capturing the offending {@code CommandLine} object.
          *
          * @param parsedCommands the {@code CommandLine} objects that resulted from successfully parsing the command line arguments
          * @param out the {@code PrintStream} to print help to if requested
          * @param ansi for printing help messages using ANSI styles and colors
          * @return an empty list if help was requested, or a list containing a single element: the result of calling the
          *      {@code Callable}, or a {@code null} element if the top-level command was a {@code Runnable}
          * @throws ExecutionException if a problem occurred while processing the parse results; use
          *      {@link ExecutionException#getCommandLine()} to get the command or subcommand where processing failed
          */
         public List<Object> handleParseResult(List<CommandLine> parsedCommands, PrintStream out, Help.Ansi ansi) {
             if (printHelpIfRequested(parsedCommands, out, ansi)) { return Collections.emptyList(); }
             return Arrays.asList(execute(parsedCommands.get(0)));
         }
     }
     /**
      * Command line parse result handler that prints help if requested, and otherwise executes the most specific
      * {@code Runnable} or {@code Callable} subcommand.
      * For use in the {@link #parseWithHandlers(IParseResultHandler, PrintStream, Help.Ansi, IExceptionHandler, String...) parseWithHandler} methods.
      * <p>
      * Something like this:</p>
      * <pre>
      *     // RunLast implementation: print help if requested, otherwise execute the most specific subcommand
      *     if (CommandLine.printHelpIfRequested(parsedCommands, System.err, Help.Ansi.AUTO)) {
      *         return emptyList();
      *     }
      *     CommandLine last = parsedCommands.get(parsedCommands.size() - 1);
      *     Object command = last.getCommand();
      *     if (command instanceof Runnable) {
      *         try {
      *             ((Runnable) command).run();
      *         } catch (Exception ex) {
      *             throw new ExecutionException(last, "Error in runnable " + command, ex);
      *         }
      *     } else if (command instanceof Callable) {
      *         Object result;
      *         try {
      *             result = ((Callable) command).call();
      *         } catch (Exception ex) {
      *             throw new ExecutionException(last, "Error in callable " + command, ex);
      *         }
      *         // ...do something with result
      *     } else {
      *         throw new ExecutionException(last, "Parsed command (" + command + ") is not Runnable or Callable");
      *     }
      * </pre>
      * @since 2.0 */
     public static class RunLast implements IParseResultHandler {
         /** Prints help if requested, and otherwise executes the most specific {@code Runnable} or {@code Callable} subcommand.
          * If the last (sub)command does not implement either {@code Runnable} or {@code Callable}, a {@code ExecutionException}
          * is thrown detailing the problem and capturing the offending {@code CommandLine} object.
          *
          * @param parsedCommands the {@code CommandLine} objects that resulted from successfully parsing the command line arguments
          * @param out the {@code PrintStream} to print help to if requested
          * @param ansi for printing help messages using ANSI styles and colors
          * @return an empty list if help was requested, or a list containing a single element: the result of calling the
          *      {@code Callable}, or a {@code null} element if the last (sub)command was a {@code Runnable}
          * @throws ExecutionException if a problem occurred while processing the parse results; use
          *      {@link ExecutionException#getCommandLine()} to get the command or subcommand where processing failed
          */
         public List<Object> handleParseResult(List<CommandLine> parsedCommands, PrintStream out, Help.Ansi ansi) {
             if (printHelpIfRequested(parsedCommands, out, ansi)) { return Collections.emptyList(); }
             CommandLine last = parsedCommands.get(parsedCommands.size() - 1);
             return Arrays.asList(execute(last));
         }
     }
     /**
      * Command line parse result handler that prints help if requested, and otherwise executes the top-level command and
      * all subcommands as {@code Runnable} or {@code Callable}.
      * For use in the {@link #parseWithHandlers(IParseResultHandler, PrintStream, Help.Ansi, IExceptionHandler, String...) parseWithHandler} methods.
      * @since 2.0 */
     public static class RunAll implements IParseResultHandler {
         /** Prints help if requested, and otherwise executes the top-level command and all subcommands as {@code Runnable}
          * or {@code Callable}. If any of the {@code CommandLine} commands does not implement either
          * {@code Runnable} or {@code Callable}, a {@code ExecutionException}
          * is thrown detailing the problem and capturing the offending {@code CommandLine} object.
          *
          * @param parsedCommands the {@code CommandLine} objects that resulted from successfully parsing the command line arguments
          * @param out the {@code PrintStream} to print help to if requested
          * @param ansi for printing help messages using ANSI styles and colors
          * @return an empty list if help was requested, or a list containing the result of executing all commands:
          *      the return values from calling the {@code Callable} commands, {@code null} elements for commands that implement {@code Runnable}
          * @throws ExecutionException if a problem occurred while processing the parse results; use
          *      {@link ExecutionException#getCommandLine()} to get the command or subcommand where processing failed
          */
         public List<Object> handleParseResult(List<CommandLine> parsedCommands, PrintStream out, Help.Ansi ansi) {
             if (printHelpIfRequested(parsedCommands, out, ansi)) {
                 return null;
             }
             List<Object> result = new ArrayList<Object>();
             for (CommandLine parsed : parsedCommands) {
                 result.add(execute(parsed));
             }
             return result;
         }
     }
     /**
      * Returns the result of calling {@link #parseWithHandlers(IParseResultHandler, PrintStream, Help.Ansi, IExceptionHandler, String...)}
      * with {@code Help.Ansi.AUTO} and a new {@link DefaultExceptionHandler} in addition to the specified parse result handler,
      * {@code PrintStream}, and the specified command line arguments.
      * <p>
      * This is a convenience method intended to offer the same ease of use as the {@link #run(Runnable, PrintStream, Help.Ansi, String...) run}
      * and {@link #call(Callable, PrintStream, Help.Ansi, String...) call} methods, but with more flexibility and better
      * support for nested subcommands.
      * </p>
      * <p>Calling this method roughly expands to:</p>
      * <pre>
      * try {
      *     List&lt;CommandLine&gt; parsedCommands = parse(args);
      *     return parseResultsHandler.handleParseResult(parsedCommands, out, Help.Ansi.AUTO);
      * } catch (ParameterException ex) {
      *     return new DefaultExceptionHandler().handleException(ex, out, ansi, args);
      * }
      * </pre>
      * <p>
      * Picocli provides some default handlers that allow you to accomplish some common tasks with very little code.
      * The following handlers are available:</p>
      * <ul>
      *   <li>{@link RunLast} handler prints help if requested, and otherwise gets the last specified command or subcommand
      * and tries to execute it as a {@code Runnable} or {@code Callable}.</li>
      *   <li>{@link RunFirst} handler prints help if requested, and otherwise executes the top-level command as a {@code Runnable} or {@code Callable}.</li>
      *   <li>{@link RunAll} handler prints help if requested, and otherwise executes all recognized commands and subcommands as {@code Runnable} or {@code Callable} tasks.</li>
      *   <li>{@link DefaultExceptionHandler} prints the error message followed by usage help</li>
      * </ul>
      * @param handler the function that will process the result of successfully parsing the command line arguments
      * @param out the {@code PrintStream} to print help to if requested
      * @param args the command line arguments
      * @return a list of results, or an empty list if there are no results
      * @throws ExecutionException if the command line arguments were parsed successfully but a problem occurred while processing the
      *      parse results; use {@link ExecutionException#getCommandLine()} to get the command or subcommand where processing failed
      * @see RunLast
      * @see RunAll
      * @since 2.0 */
     public List<Object> parseWithHandler(IParseResultHandler handler, PrintStream out, String... args) {
         return parseWithHandlers(handler, out, Help.Ansi.AUTO, new DefaultExceptionHandler(), args);
     }
     /**
      * Tries to {@linkplain #parse(String...) parse} the specified command line arguments, and if successful, delegates
      * the processing of the resulting list of {@code CommandLine} objects to the specified {@linkplain IParseResultHandler handler}.
      * If the command line arguments were invalid, the {@code ParameterException} thrown from the {@code parse} method
      * is caught and passed to the specified {@link IExceptionHandler}.
      * <p>
      * This is a convenience method intended to offer the same ease of use as the {@link #run(Runnable, PrintStream, Help.Ansi, String...) run}
      * and {@link #call(Callable, PrintStream, Help.Ansi, String...) call} methods, but with more flexibility and better
      * support for nested subcommands.
      * </p>
      * <p>Calling this method roughly expands to:</p>
      * <pre>
      * try {
      *     List&lt;CommandLine&gt; parsedCommands = parse(args);
      *     return parseResultsHandler.handleParseResult(parsedCommands, out, ansi);
      * } catch (ParameterException ex) {
      *     return new exceptionHandler.handleException(ex, out, ansi, args);
      * }
      * </pre>
      * <p>
      * Picocli provides some default handlers that allow you to accomplish some common tasks with very little code.
      * The following handlers are available:</p>
      * <ul>
      *   <li>{@link RunLast} handler prints help if requested, and otherwise gets the last specified command or subcommand
      * and tries to execute it as a {@code Runnable} or {@code Callable}.</li>
      *   <li>{@link RunFirst} handler prints help if requested, and otherwise executes the top-level command as a {@code Runnable} or {@code Callable}.</li>
      *   <li>{@link RunAll} handler prints help if requested, and otherwise executes all recognized commands and subcommands as {@code Runnable} or {@code Callable} tasks.</li>
      *   <li>{@link DefaultExceptionHandler} prints the error message followed by usage help</li>
      * </ul>
      *
      * @param handler the function that will process the result of successfully parsing the command line arguments
      * @param out the {@code PrintStream} to print help to if requested
      * @param ansi for printing help messages using ANSI styles and colors
      * @param exceptionHandler the function that can handle the {@code ParameterException} thrown when the command line arguments are invalid
      * @param args the command line arguments
      * @return a list of results produced by the {@code IParseResultHandler} or the {@code IExceptionHandler}, or an empty list if there are no results
      * @throws ExecutionException if the command line arguments were parsed successfully but a problem occurred while processing the parse
      *      result {@code CommandLine} objects; use {@link ExecutionException#getCommandLine()} to get the command or subcommand where processing failed
      * @see RunLast
      * @see RunAll
      * @see DefaultExceptionHandler
      * @since 2.0 */
     public List<Object> parseWithHandlers(IParseResultHandler handler, PrintStream out, Help.Ansi ansi, IExceptionHandler exceptionHandler, String... args) {
         try {
             List<CommandLine> result = parse(args);
             return handler.handleParseResult(result, out, ansi);
         } catch (ParameterException ex) {
             return exceptionHandler.handleException(ex, out, ansi, args);
         }
     }
     /**
      * Equivalent to {@code new CommandLine(command).usage(out)}. See {@link #usage(PrintStream)} for details.
      * @param command the object annotated with {@link Command}, {@link Option} and {@link Parameters}
      * @param out the print stream to print the help message to
      * @throws IllegalArgumentException if the specified command object does not have a {@link Command}, {@link Option} or {@link Parameters} annotation
      */
     public static void usage(Object command, PrintStream out) {
         toCommandLine(command).usage(out);
     }
 
     /**
      * Equivalent to {@code new CommandLine(command).usage(out, ansi)}.
      * See {@link #usage(PrintStream, Help.Ansi)} for details.
      * @param command the object annotated with {@link Command}, {@link Option} and {@link Parameters}
      * @param out the print stream to print the help message to
      * @param ansi whether the usage message should contain ANSI escape codes or not
      * @throws IllegalArgumentException if the specified command object does not have a {@link Command}, {@link Option} or {@link Parameters} annotation
      */
     public static void usage(Object command, PrintStream out, Help.Ansi ansi) {
         toCommandLine(command).usage(out, ansi);
     }
 
     /**
      * Equivalent to {@code new CommandLine(command).usage(out, colorScheme)}.
      * See {@link #usage(PrintStream, Help.ColorScheme)} for details.
      * @param command the object annotated with {@link Command}, {@link Option} and {@link Parameters}
      * @param out the print stream to print the help message to
      * @param colorScheme the {@code ColorScheme} defining the styles for options, parameters and commands when ANSI is enabled
      * @throws IllegalArgumentException if the specified command object does not have a {@link Command}, {@link Option} or {@link Parameters} annotation
      */
     public static void usage(Object command, PrintStream out, Help.ColorScheme colorScheme) {
         toCommandLine(command).usage(out, colorScheme);
     }
 
     /**
      * Delegates to {@link #usage(PrintStream, Help.Ansi)} with the {@linkplain Help.Ansi#AUTO platform default}.
      * @param out the printStream to print to
      * @see #usage(PrintStream, Help.ColorScheme)
      */
     public void usage(PrintStream out) {
         usage(out, Help.Ansi.AUTO);
     }
 
     /**
      * Delegates to {@link #usage(PrintStream, Help.ColorScheme)} with the {@linkplain Help#defaultColorScheme(CommandLine.Help.Ansi) default color scheme}.
      * @param out the printStream to print to
      * @param ansi whether the usage message should include ANSI escape codes or not
      * @see #usage(PrintStream, Help.ColorScheme)
      */
     public void usage(PrintStream out, Help.Ansi ansi) {
         usage(out, Help.defaultColorScheme(ansi));
     }
     /**
      * Prints a usage help message for the annotated command class to the specified {@code PrintStream}.
      * Delegates construction of the usage help message to the {@link Help} inner class and is equivalent to:
      * <pre>
      * Help help = new Help(command).addAllSubcommands(getSubcommands());
      * StringBuilder sb = new StringBuilder()
      *         .append(help.headerHeading())
      *         .append(help.header())
      *         .append(help.synopsisHeading())      //e.g. Usage:
      *         .append(help.synopsis())             //e.g. &lt;main class&gt; [OPTIONS] &lt;command&gt; [COMMAND-OPTIONS] [ARGUMENTS]
      *         .append(help.descriptionHeading())   //e.g. %nDescription:%n%n
      *         .append(help.description())          //e.g. {"Converts foos to bars.", "Use options to control conversion mode."}
      *         .append(help.parameterListHeading()) //e.g. %nPositional parameters:%n%n
      *         .append(help.parameterList())        //e.g. [FILE...] the files to convert
      *         .append(help.optionListHeading())    //e.g. %nOptions:%n%n
      *         .append(help.optionList())           //e.g. -h, --help   displays this help and exits
      *         .append(help.commandListHeading())   //e.g. %nCommands:%n%n
      *         .append(help.commandList())          //e.g.    add       adds the frup to the frooble
      *         .append(help.footerHeading())
      *         .append(help.footer());
      * out.print(sb);
      * </pre>
      * <p>Annotate your class with {@link Command} to control many aspects of the usage help message, including
      * the program name, text of section headings and section contents, and some aspects of the auto-generated sections
      * of the usage help message.
      * <p>To customize the auto-generated sections of the usage help message, like how option details are displayed,
      * instantiate a {@link Help} object and use a {@link Help.TextTable} with more of fewer columns, a custom
      * {@linkplain Help.Layout layout}, and/or a custom option {@linkplain Help.IOptionRenderer renderer}
      * for ultimate control over which aspects of an Option or Field are displayed where.</p>
      * @param out the {@code PrintStream} to print the usage help message to
      * @param colorScheme the {@code ColorScheme} defining the styles for options, parameters and commands when ANSI is enabled
      */
     public void usage(PrintStream out, Help.ColorScheme colorScheme) {
         Help help = new Help(interpreter.command, colorScheme).addAllSubcommands(getSubcommands());
         if (!Help.DEFAULT_SEPARATOR.equals(getSeparator())) {
             help.separator = getSeparator();
             help.parameterLabelRenderer = help.createDefaultParamLabelRenderer(); // update for new separator
         }
         if (!Help.DEFAULT_COMMAND_NAME.equals(getCommandName())) {
             help.commandName = getCommandName();
         }
         StringBuilder sb = new StringBuilder()
                 .append(help.headerHeading())
                 .append(help.header())
                 .append(help.synopsisHeading())      //e.g. Usage:
                 .append(help.synopsis(help.synopsisHeadingLength())) //e.g. &lt;main class&gt; [OPTIONS] &lt;command&gt; [COMMAND-OPTIONS] [ARGUMENTS]
                 .append(help.descriptionHeading())   //e.g. %nDescription:%n%n
                 .append(help.description())          //e.g. {"Converts foos to bars.", "Use options to control conversion mode."}
                 .append(help.parameterListHeading()) //e.g. %nPositional parameters:%n%n
                 .append(help.parameterList())        //e.g. [FILE...] the files to convert
                 .append(help.optionListHeading())    //e.g. %nOptions:%n%n
                 .append(help.optionList())           //e.g. -h, --help   displays this help and exits
                 .append(help.commandListHeading())   //e.g. %nCommands:%n%n
                 .append(help.commandList())          //e.g.    add       adds the frup to the frooble
                 .append(help.footerHeading())
                 .append(help.footer());
         out.print(sb);
     }
 
     /**
      * Delegates to {@link #printVersionHelp(PrintStream, Help.Ansi)} with the {@linkplain Help.Ansi#AUTO platform default}.
      * @param out the printStream to print to
      * @see #printVersionHelp(PrintStream, Help.Ansi)
      * @since 0.9.8
      */
     public void printVersionHelp(PrintStream out) { printVersionHelp(out, Help.Ansi.AUTO); }
 
     /**
      * Prints version information from the {@link Command#version()} annotation to the specified {@code PrintStream}.
      * Each element of the array of version strings is printed on a separate line. Version strings may contain
      * <a href="http://picocli.info/#_usage_help_with_styles_and_colors">markup for colors and style</a>.
      * @param out the printStream to print to
      * @param ansi whether the usage message should include ANSI escape codes or not
      * @see Command#version()
      * @see Option#versionHelp()
      * @see #isVersionHelpRequested()
      * @since 0.9.8
      */
     public void printVersionHelp(PrintStream out, Help.Ansi ansi) {
         for (String versionInfo : versionLines) {
             out.println(ansi.new Text(versionInfo));
         }
     }
     /**
      * Prints version information from the {@link Command#version()} annotation to the specified {@code PrintStream}.
      * Each element of the array of version strings is {@linkplain String#format(String, Object...) formatted} with the
      * specified parameters, and printed on a separate line. Both version strings and parameters may contain
      * <a href="http://picocli.info/#_usage_help_with_styles_and_colors">markup for colors and style</a>.
      * @param out the printStream to print to
      * @param ansi whether the usage message should include ANSI escape codes or not
      * @param params Arguments referenced by the format specifiers in the version strings
      * @see Command#version()
      * @see Option#versionHelp()
      * @see #isVersionHelpRequested()
      * @since 1.0.0
      */
     public void printVersionHelp(PrintStream out, Help.Ansi ansi, Object... params) {
         for (String versionInfo : versionLines) {
             out.println(ansi.new Text(String.format(versionInfo, params)));
         }
     }
 
     /**
      * Delegates to {@link #call(Callable, PrintStream, Help.Ansi, String...)} with {@link Help.Ansi#AUTO}.
      * <p>
      * From picocli v2.0, this method prints usage help or version help if {@linkplain #printHelpIfRequested(List, PrintStream, Help.Ansi) requested},
      * and any exceptions thrown by the {@code Callable} are caught and rethrown wrapped in an {@code ExecutionException}.
      * </p>
      * @param callable the command to call when {@linkplain #parse(String...) parsing} succeeds.
      * @param out the printStream to print to
      * @param args the command line arguments to parse
      * @param <C> the annotated object must implement Callable
      * @param <T> the return type of the most specific command (must implement {@code Callable})
      * @see #call(Callable, PrintStream, Help.Ansi, String...)
      * @throws InitializationException if the specified command object does not have a {@link Command}, {@link Option} or {@link Parameters} annotation
      * @throws ExecutionException if the Callable throws an exception
      * @return {@code null} if an error occurred while parsing the command line options, otherwise returns the result of calling the Callable
      * @see #parseWithHandlers(IParseResultHandler, PrintStream, Help.Ansi, IExceptionHandler, String...)
      * @see RunFirst
      */
     public static <C extends Callable<T>, T> T call(C callable, PrintStream out, String... args) {
         return call(callable, out, Help.Ansi.AUTO, args);
     }
     /**
      * Convenience method to allow command line application authors to avoid some boilerplate code in their application.
      * The annotated object needs to implement {@link Callable}. Calling this method is equivalent to:
      * <pre>
      * CommandLine cmd = new CommandLine(callable);
      * List&lt;CommandLine&gt; parsedCommands;
      * try {
      *     parsedCommands = cmd.parse(args);
      * } catch (ParameterException ex) {
      *     out.println(ex.getMessage());
      *     cmd.usage(out, ansi);
      *     return null;
      * }
      * if (CommandLine.printHelpIfRequested(parsedCommands, out, ansi)) {
      *     return null;
      * }
      * CommandLine last = parsedCommands.get(parsedCommands.size() - 1);
      * try {
      *     Callable&lt;Object&gt; subcommand = last.getCommand();
      *     return subcommand.call();
      * } catch (Exception ex) {
      *     throw new ExecutionException(last, "Error calling " + last.getCommand(), ex);
      * }
      * </pre>
      * <p>
      * If the specified Callable command has subcommands, the {@linkplain RunLast last} subcommand specified on the
      * command line is executed.
      * Commands with subcommands may be interested in calling the {@link #parseWithHandler(IParseResultHandler, PrintStream, String...) parseWithHandler}
      * method with a {@link RunAll} handler or a custom handler.
      * </p><p>
      * From picocli v2.0, this method prints usage help or version help if {@linkplain #printHelpIfRequested(List, PrintStream, Help.Ansi) requested},
      * and any exceptions thrown by the {@code Callable} are caught and rethrown wrapped in an {@code ExecutionException}.
      * </p>
      * @param callable the command to call when {@linkplain #parse(String...) parsing} succeeds.
      * @param out the printStream to print to
      * @param ansi whether the usage message should include ANSI escape codes or not
      * @param args the command line arguments to parse
      * @param <C> the annotated object must implement Callable
      * @param <T> the return type of the specified {@code Callable}
      * @throws InitializationException if the specified command object does not have a {@link Command}, {@link Option} or {@link Parameters} annotation
      * @throws ExecutionException if the Callable throws an exception
      * @return {@code null} if an error occurred while parsing the command line options, or if help was requested and printed. Otherwise returns the result of calling the Callable
      * @see #parseWithHandlers(IParseResultHandler, PrintStream, Help.Ansi, IExceptionHandler, String...)
      * @see RunLast
      */
     public static <C extends Callable<T>, T> T call(C callable, PrintStream out, Help.Ansi ansi, String... args) {
         CommandLine cmd = new CommandLine(callable); // validate command outside of try-catch
         List<Object> results = cmd.parseWithHandlers(new RunLast(), out, ansi, new DefaultExceptionHandler(), args);
         return results == null || results.isEmpty() ? null : (T) results.get(0);
     }
 
     /**
      * Delegates to {@link #run(Runnable, PrintStream, Help.Ansi, String...)} with {@link Help.Ansi#AUTO}.
      * <p>
      * From picocli v2.0, this method prints usage help or version help if {@linkplain #printHelpIfRequested(List, PrintStream, Help.Ansi) requested},
      * and any exceptions thrown by the {@code Runnable} are caught and rethrown wrapped in an {@code ExecutionException}.
      * </p>
      * @param runnable the command to run when {@linkplain #parse(String...) parsing} succeeds.
      * @param out the printStream to print to
      * @param args the command line arguments to parse
      * @param <R> the annotated object must implement Runnable
      * @see #run(Runnable, PrintStream, Help.Ansi, String...)
      * @throws InitializationException if the specified command object does not have a {@link Command}, {@link Option} or {@link Parameters} annotation
      * @throws ExecutionException if the Runnable throws an exception
      * @see #parseWithHandlers(IParseResultHandler, PrintStream, Help.Ansi, IExceptionHandler, String...)
      * @see RunFirst
      */
     public static <R extends Runnable> void run(R runnable, PrintStream out, String... args) {
         run(runnable, out, Help.Ansi.AUTO, args);
     }
     /**
      * Convenience method to allow command line application authors to avoid some boilerplate code in their application.
      * The annotated object needs to implement {@link Runnable}. Calling this method is equivalent to:
      * <pre>
      * CommandLine cmd = new CommandLine(runnable);
      * List&lt;CommandLine&gt; parsedCommands;
      * try {
      *     parsedCommands = cmd.parse(args);
      * } catch (ParameterException ex) {
      *     out.println(ex.getMessage());
      *     cmd.usage(out, ansi);
      *     return null;
      * }
      * if (CommandLine.printHelpIfRequested(parsedCommands, out, ansi)) {
      *     return null;
      * }
      * CommandLine last = parsedCommands.get(parsedCommands.size() - 1);
      * try {
      *     Runnable subcommand = last.getCommand();
      *     subcommand.run();
      * } catch (Exception ex) {
      *     throw new ExecutionException(last, "Error running " + last.getCommand(), ex);
      * }
      * </pre>
      * <p>
      * If the specified Runnable command has subcommands, the {@linkplain RunLast last} subcommand specified on the
      * command line is executed.
      * Commands with subcommands may be interested in calling the {@link #parseWithHandler(IParseResultHandler, PrintStream, String...) parseWithHandler}
      * method with a {@link RunAll} handler or a custom handler.
      * </p><p>
      * From picocli v2.0, this method prints usage help or version help if {@linkplain #printHelpIfRequested(List, PrintStream, Help.Ansi) requested},
      * and any exceptions thrown by the {@code Runnable} are caught and rethrown wrapped in an {@code ExecutionException}.
      * </p>
      * @param runnable the command to run when {@linkplain #parse(String...) parsing} succeeds.
      * @param out the printStream to print to
      * @param ansi whether the usage message should include ANSI escape codes or not
      * @param args the command line arguments to parse
      * @param <R> the annotated object must implement Runnable
      * @throws InitializationException if the specified command object does not have a {@link Command}, {@link Option} or {@link Parameters} annotation
      * @throws ExecutionException if the Runnable throws an exception
      * @see #parseWithHandlers(IParseResultHandler, PrintStream, Help.Ansi, IExceptionHandler, String...)
      * @see RunLast
      */
     public static <R extends Runnable> void run(R runnable, PrintStream out, Help.Ansi ansi, String... args) {
         CommandLine cmd = new CommandLine(runnable); // validate command outside of try-catch
         cmd.parseWithHandlers(new RunLast(), out, ansi, new DefaultExceptionHandler(), args);
     }
 
     /**
      * Registers the specified type converter for the specified class. When initializing fields annotated with
      * {@link Option}, the field's type is used as a lookup key to find the associated type converter, and this
      * type converter converts the original command line argument string value to the correct type.
      * <p>
      * Java 8 lambdas make it easy to register custom type converters:
      * </p>
      * <pre>
      * commandLine.registerConverter(java.nio.file.Path.class, s -&gt; java.nio.file.Paths.get(s));
      * commandLine.registerConverter(java.time.Duration.class, s -&gt; java.time.Duration.parse(s));</pre>
      * <p>
      * Built-in type converters are pre-registered for the following java 1.5 types:
      * </p>
      * <ul>
      *   <li>all primitive types</li>
      *   <li>all primitive wrapper types: Boolean, Byte, Character, Double, Float, Integer, Long, Short</li>
      *   <li>any enum</li>
      *   <li>java.io.File</li>
      *   <li>java.math.BigDecimal</li>
      *   <li>java.math.BigInteger</li>
      *   <li>java.net.InetAddress</li>
      *   <li>java.net.URI</li>
      *   <li>java.net.URL</li>
      *   <li>java.nio.charset.Charset</li>
      *   <li>java.sql.Time</li>
      *   <li>java.util.Date</li>
      *   <li>java.util.UUID</li>
      *   <li>java.util.regex.Pattern</li>
      *   <li>StringBuilder</li>
      *   <li>CharSequence</li>
      *   <li>String</li>
      * </ul>
      * <p>The specified converter will be registered with this {@code CommandLine} and the full hierarchy of its
      * subcommands and nested sub-subcommands <em>at the moment the converter is registered</em>. Subcommands added
      * later will not have this converter added automatically. To ensure a custom type converter is available to all
      * subcommands, register the type converter last, after adding subcommands.</p>
      *
      * @param cls the target class to convert parameter string values to
      * @param converter the class capable of converting string values to the specified target type
      * @param <K> the target type
      * @return this CommandLine object, to allow method chaining
      * @see #addSubcommand(String, Object)
      */
     public <K> CommandLine registerConverter(Class<K> cls, ITypeConverter<K> converter) {
         interpreter.converterRegistry.put(Assert.notNull(cls, "class"), Assert.notNull(converter, "converter"));
         for (CommandLine command : interpreter.commands.values()) {
             command.registerConverter(cls, converter);
         }
         return this;
     }
 
     /** Returns the String that separates option names from option values when parsing command line options. {@value Help#DEFAULT_SEPARATOR} by default.
      * @return the String the parser uses to separate option names from option values */
     public String getSeparator() {
         return interpreter.separator;
     }
 
     /** Sets the String the parser uses to separate option names from option values to the specified value.
      * The separator may also be set declaratively with the {@link CommandLine.Command#separator()} annotation attribute.
      * @param separator the String that separates option names from option values
      * @return this {@code CommandLine} object, to allow method chaining */
     public CommandLine setSeparator(String separator) {
         interpreter.separator = Assert.notNull(separator, "separator");
         return this;
     }
 
     /** Returns the command name (also called program name) displayed in the usage help synopsis. {@value Help#DEFAULT_COMMAND_NAME} by default.
      * @return the command name (also called program name) displayed in the usage */
     public String getCommandName() {
         return commandName;
     }
 
     /** Sets the command name (also called program name) displayed in the usage help synopsis to the specified value.
      * Note that this method only modifies the usage help message, it does not impact parsing behaviour.
      * The command name may also be set declaratively with the {@link CommandLine.Command#name()} annotation attribute.
      * @param commandName command name (also called program name) displayed in the usage help synopsis
      * @return this {@code CommandLine} object, to allow method chaining */
     public CommandLine setCommandName(String commandName) {
         this.commandName = Assert.notNull(commandName, "commandName");
         return this;
     }
     private static boolean empty(String str) { return str == null || str.trim().length() == 0; }
     private static boolean empty(Object[] array) { return array == null || array.length == 0; }
     private static boolean empty(Text txt) { return txt == null || txt.plain.toString().trim().length() == 0; }
     private static String str(String[] arr, int i) { return (arr == null || arr.length == 0) ? "" : arr[i]; }
     private static boolean isBoolean(Class<?> type) { return type == Boolean.class || type == Boolean.TYPE; }
     private static CommandLine toCommandLine(Object obj) { return obj instanceof CommandLine ? (CommandLine) obj : new CommandLine(obj);}
     private static boolean isMultiValue(Field field) {  return isMultiValue(field.getType()); }
     private static boolean isMultiValue(Class<?> cls) { return cls.isArray() || Collection.class.isAssignableFrom(cls) || Map.class.isAssignableFrom(cls); }
     private static Class<?>[] getTypeAttribute(Field field) {
         Class<?>[] explicit = field.isAnnotationPresent(Parameters.class) ? field.getAnnotation(Parameters.class).type() : field.getAnnotation(Option.class).type();
         if (explicit.length > 0) { return explicit; }
         if (field.getType().isArray()) { return new Class<?>[] { field.getType().getComponentType() }; }
         if (isMultiValue(field)) {
             Type type = field.getGenericType(); // e.g. Map<Long, ? extends Number>
             if (type instanceof ParameterizedType) {
                 ParameterizedType parameterizedType = (ParameterizedType) type;
                 Type[] paramTypes = parameterizedType.getActualTypeArguments(); // e.g. ? extends Number
                 Class<?>[] result = new Class<?>[paramTypes.length];
                 for (int i = 0; i < paramTypes.length; i++) {
                     if (paramTypes[i] instanceof Class) { result[i] = (Class<?>) paramTypes[i]; continue; } // e.g. Long
                     if (paramTypes[i] instanceof WildcardType) { // e.g. ? extends Number
                         WildcardType wildcardType = (WildcardType) paramTypes[i];
                         Type[] lower = wildcardType.getLowerBounds(); // e.g. []
                         if (lower.length > 0 && lower[0] instanceof Class) { result[i] = (Class<?>) lower[0]; continue; }
                         Type[] upper = wildcardType.getUpperBounds(); // e.g. Number
                         if (upper.length > 0 && upper[0] instanceof Class) { result[i] = (Class<?>) upper[0]; continue; }
                     }
                     Arrays.fill(result, String.class); return result; // too convoluted generic type, giving up
                 }
                 return result; // we inferred all types from ParameterizedType
             }
             return new Class<?>[] {String.class, String.class}; // field is multi-value but not ParameterizedType
         }
         return new Class<?>[] {field.getType()}; // not a multi-value field
     }
     /**
      * <p>
      * Annotate fields in your class with {@code @Option} and picocli will initialize these fields when matching
      * arguments are specified on the command line.
      * </p><p>
      * For example:
      * </p>
      * <pre>import static picocli.CommandLine.*;
      *
      * public class MyClass {
      *     &#064;Parameters(type = File.class, description = "Any number of input files")
      *     private List&lt;File&gt; files = new ArrayList&lt;File&gt;();
      *
      *     &#064;Option(names = { "-o", "--out" }, description = "Output file (default: print to console)")
      *     private File outputFile;
      *
      *     &#064;Option(names = { "-v", "--verbose"}, description = "Verbosely list files processed")
      *     private boolean verbose;
      *
      *     &#064;Option(names = { "-h", "--help", "-?", "-help"}, usageHelp = true, description = "Display this help and exit")
      *     private boolean help;
      *
      *     &#064;Option(names = { "-V", "--version"}, versionHelp = true, description = "Display version information and exit")
      *     private boolean version;
      * }
      * </pre>
      * <p>
      * A field cannot be annotated with both {@code @Parameters} and {@code @Option} or a
      * {@code ParameterException} is thrown.
      * </p>
      */
     @Retention(RetentionPolicy.RUNTIME)
     @Target(ElementType.FIELD)
     public @interface Option {
         /**
          * One or more option names. At least one option name is required.
          * <p>
          * Different environments have different conventions for naming options, but usually options have a prefix
          * that sets them apart from parameters.
          * Picocli supports all of the below styles. The default separator is {@code '='}, but this can be configured.
          * </p><p>
          * <b>*nix</b>
          * </p><p>
          * In Unix and Linux, options have a short (single-character) name, a long name or both.
          * Short options
          * (<a href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap12.html#tag_12_02">POSIX
          * style</a> are single-character and are preceded by the {@code '-'} character, e.g., {@code `-v'}.
          * <a href="https://www.gnu.org/software/tar/manual/html_node/Long-Options.html">GNU-style</a> long
          * (or <em>mnemonic</em>) options start with two dashes in a row, e.g., {@code `--file'}.
          * </p><p>Picocli supports the POSIX convention that short options can be grouped, with the last option
          * optionally taking a parameter, which may be attached to the option name or separated by a space or
          * a {@code '='} character. The below examples are all equivalent:
          * </p><pre>
          * -xvfFILE
          * -xvf FILE
          * -xvf=FILE
          * -xv --file FILE
          * -xv --file=FILE
          * -x -v --file FILE
          * -x -v --file=FILE
          * </pre><p>
          * <b>DOS</b>
          * </p><p>
          * DOS options mostly have upper case single-character names and start with a single slash {@code '/'} character.
          * Option parameters are separated by a {@code ':'} character. Options cannot be grouped together but
          * must be specified separately. For example:
          * </p><pre>
          * DIR /S /A:D /T:C
          * </pre><p>
          * <b>PowerShell</b>
          * </p><p>
          * Windows PowerShell options generally are a word preceded by a single {@code '-'} character, e.g., {@code `-Help'}.
          * Option parameters are separated by a space or by a {@code ':'} character.
          * </p>
          * @return one or more option names
          */
         String[] names();
 
         /**
          * Indicates whether this option is required. By default this is false.
          * If an option is required, but a user invokes the program without specifying the required option,
          * a {@link MissingParameterException} is thrown from the {@link #parse(String...)} method.
          * @return whether this option is required
          */
         boolean required() default false;
 
         /**
          * Set {@code help=true} if this option should disable validation of the remaining arguments:
          * If the {@code help} option is specified, no error message is generated for missing required options.
          * <p>
          * This attribute is useful for special options like help ({@code -h} and {@code --help} on unix,
          * {@code -?} and {@code -Help} on Windows) or version ({@code -V} and {@code --version} on unix,
          * {@code -Version} on Windows).
          * </p>
          * <p>
          * Note that the {@link #parse(String...)} method will not print help documentation. It will only set
          * the value of the annotated field. It is the responsibility of the caller to inspect the annotated fields
          * and take the appropriate action.
          * </p>
          * @return whether this option disables validation of the other arguments
          * @deprecated Use {@link #usageHelp()} and {@link #versionHelp()} instead. See {@link #printHelpIfRequested(List, PrintStream, CommandLine.Help.Ansi)}
          */
         boolean help() default false;
 
         /**
          * Set {@code usageHelp=true} if this option allows the user to request usage help. If this option is
          * specified on the command line, picocli will not validate the remaining arguments (so no "missing required
          * option" errors) and the {@link CommandLine#isUsageHelpRequested()} method will return {@code true}.
          * <p>
          * This attribute is useful for special options like help ({@code -h} and {@code --help} on unix,
          * {@code -?} and {@code -Help} on Windows).
          * </p>
          * <p>
          * Note that the {@link #parse(String...)} method will not print usage help documentation. It will only set
          * the value of the annotated field. It is the responsibility of the caller to inspect the annotated fields
          * and take the appropriate action.
          * </p>
          * @return whether this option allows the user to request usage help
          * @since 0.9.8
          */
         boolean usageHelp() default false;
 
         /**
          * Set {@code versionHelp=true} if this option allows the user to request version information. If this option is
          * specified on the command line, picocli will not validate the remaining arguments (so no "missing required
          * option" errors) and the {@link CommandLine#isVersionHelpRequested()} method will return {@code true}.
          * <p>
          * This attribute is useful for special options like version ({@code -V} and {@code --version} on unix,
          * {@code -Version} on Windows).
          * </p>
          * <p>
          * Note that the {@link #parse(String...)} method will not print version information. It will only set
          * the value of the annotated field. It is the responsibility of the caller to inspect the annotated fields
          * and take the appropriate action.
          * </p>
          * @return whether this option allows the user to request version information
          * @since 0.9.8
          */
         boolean versionHelp() default false;
 
         /**
          * Description of this option, used when generating the usage documentation.
          * @return the description of this option
          */
         String[] description() default {};
 
         /**
          * Specifies the minimum number of required parameters and the maximum number of accepted parameters.
          * If an option declares a positive arity, and the user specifies an insufficient number of parameters on the
          * command line, a {@link MissingParameterException} is thrown by the {@link #parse(String...)} method.
          * <p>
          * In many cases picocli can deduce the number of required parameters from the field's type.
          * By default, flags (boolean options) have arity zero,
          * and single-valued type fields (String, int, Integer, double, Double, File, Date, etc) have arity one.
          * Generally, fields with types that cannot hold multiple values can omit the {@code arity} attribute.
          * </p><p>
          * Fields used to capture options with arity two or higher should have a type that can hold multiple values,
          * like arrays or Collections. See {@link #type()} for strongly-typed Collection fields.
          * </p><p>
          * For example, if an option has 2 required parameters and any number of optional parameters,
          * specify {@code @Option(names = "-example", arity = "2..*")}.
          * </p>
          * <b>A note on boolean options</b>
          * <p>
          * By default picocli does not expect boolean options (also called "flags" or "switches") to have a parameter.
          * You can make a boolean option take a required parameter by annotating your field with {@code arity="1"}.
          * For example: </p>
          * <pre>&#064;Option(names = "-v", arity = "1") boolean verbose;</pre>
          * <p>
          * Because this boolean field is defined with arity 1, the user must specify either {@code <program> -v false}
          * or {@code <program> -v true}
          * on the command line, or a {@link MissingParameterException} is thrown by the {@link #parse(String...)}
          * method.
          * </p><p>
          * To make the boolean parameter possible but optional, define the field with {@code arity = "0..1"}.
          * For example: </p>
          * <pre>&#064;Option(names="-v", arity="0..1") boolean verbose;</pre>
          * <p>This will accept any of the below without throwing an exception:</p>
          * <pre>
          * -v
          * -v true
          * -v false
          * </pre>
          * @return how many arguments this option requires
          */
         String arity() default "";
 
         /**
          * Specify a {@code paramLabel} for the option parameter to be used in the usage help message. If omitted,
          * picocli uses the field name in fish brackets ({@code '<'} and {@code '>'}) by default. Example:
          * <pre>class Example {
          *     &#064;Option(names = {"-o", "--output"}, paramLabel="FILE", description="path of the output file")
          *     private File out;
          *     &#064;Option(names = {"-j", "--jobs"}, arity="0..1", description="Allow N jobs at once; infinite jobs with no arg.")
          *     private int maxJobs = -1;
          * }</pre>
          * <p>By default, the above gives a usage help message like the following:</p><pre>
          * Usage: &lt;main class&gt; [OPTIONS]
          * -o, --output FILE       path of the output file
          * -j, --jobs [&lt;maxJobs&gt;]  Allow N jobs at once; infinite jobs with no arg.
          * </pre>
          * @return name of the option parameter used in the usage help message
          */
         String paramLabel() default "";
 
         /** <p>
          * Optionally specify a {@code type} to control exactly what Class the option parameter should be converted
          * to. This may be useful when the field type is an interface or an abstract class. For example, a field can
          * be declared to have type {@code java.lang.Number}, and annotating {@code @Option(type=Short.class)}
          * ensures that the option parameter value is converted to a {@code Short} before setting the field value.
          * </p><p>
          * For array fields whose <em>component</em> type is an interface or abstract class, specify the concrete <em>component</em> type.
          * For example, a field with type {@code Number[]} may be annotated with {@code @Option(type=Short.class)}
          * to ensure that option parameter values are converted to {@code Short} before adding an element to the array.
          * </p><p>
          * Picocli will use the {@link ITypeConverter} that is
          * {@linkplain #registerConverter(Class, ITypeConverter) registered} for the specified type to convert
          * the raw String values before modifying the field value.
          * </p><p>
          * Prior to 2.0, the {@code type} attribute was necessary for {@code Collection} and {@code Map} fields,
          * but starting from 2.0 picocli will infer the component type from the generic type's type arguments.
          * For example, for a field of type {@code Map<TimeUnit, Long>} picocli will know the option parameter
          * should be split up in key=value pairs, where the key should be converted to a {@code java.util.concurrent.TimeUnit}
          * enum value, and the value should be converted to a {@code Long}. No {@code @Option(type=...)} type attribute
          * is required for this. For generic types with wildcards, picocli will take the specified upper or lower bound
          * as the Class to convert to, unless the {@code @Option} annotation specifies an explicit {@code type} attribute.
          * </p><p>
          * If the field type is a raw collection or a raw map, and you want it to contain other values than Strings,
          * or if the generic type's type arguments are interfaces or abstract classes, you may
          * specify a {@code type} attribute to control the Class that the option parameter should be converted to.
          * @return the type(s) to convert the raw String values
          */
         Class<?>[] type() default {};
 
         /**
          * Specify a regular expression to use to split option parameter values before applying them to the field.
          * All elements resulting from the split are added to the array or Collection. Ignored for single-value fields.
          * @return a regular expression to split option parameter values or {@code ""} if the value should not be split
          * @see String#split(String)
          */
         String split() default "";
 
         /**
          * Set {@code hidden=true} if this option should not be included in the usage documentation.
          * @return whether this option should be excluded from the usage message
          */
         boolean hidden() default false;
     }
     /**
      * <p>
      * Fields annotated with {@code @Parameters} will be initialized with positional parameters. By specifying the
      * {@link #index()} attribute you can pick which (or what range) of the positional parameters to apply. If no index
      * is specified, the field will get all positional parameters (so it should be an array or a collection).
      * </p><p>
      * When parsing the command line arguments, picocli first tries to match arguments to {@link Option Options}.
      * Positional parameters are the arguments that follow the options, or the arguments that follow a "--" (double
      * dash) argument on the command line.
      * </p><p>
      * For example:
      * </p>
      * <pre>import static picocli.CommandLine.*;
      *
      * public class MyCalcParameters {
      *     &#064;Parameters(type = BigDecimal.class, description = "Any number of input numbers")
      *     private List&lt;BigDecimal&gt; files = new ArrayList&lt;BigDecimal&gt;();
      *
      *     &#064;Option(names = { "-h", "--help", "-?", "-help"}, help = true, description = "Display this help and exit")
      *     private boolean help;
      * }
      * </pre><p>
      * A field cannot be annotated with both {@code @Parameters} and {@code @Option} or a {@code ParameterException}
      * is thrown.</p>
      */
     @Retention(RetentionPolicy.RUNTIME)
     @Target(ElementType.FIELD)
     public @interface Parameters {
         /** Specify an index ("0", or "1", etc.) to pick which of the command line arguments should be assigned to this
          * field. For array or Collection fields, you can also specify an index range ("0..3", or "2..*", etc.) to assign
          * a subset of the command line arguments to this field. The default is "*", meaning all command line arguments.
          * @return an index or range specifying which of the command line arguments should be assigned to this field
          */
         String index() default "*";
 
         /** Description of the parameter(s), used when generating the usage documentation.
          * @return the description of the parameter(s)
          */
         String[] description() default {};
 
         /**
          * Specifies the minimum number of required parameters and the maximum number of accepted parameters. If a
          * positive arity is declared, and the user specifies an insufficient number of parameters on the command line,
          * {@link MissingParameterException} is thrown by the {@link #parse(String...)} method.
          * <p>The default depends on the type of the parameter: booleans require no parameters, arrays and Collections
          * accept zero to any number of parameters, and any other type accepts one parameter.</p>
          * @return the range of minimum and maximum parameters accepted by this command
          */
         String arity() default "";
 
         /**
          * Specify a {@code paramLabel} for the parameter to be used in the usage help message. If omitted,
          * picocli uses the field name in fish brackets ({@code '<'} and {@code '>'}) by default. Example:
          * <pre>class Example {
          *     &#064;Parameters(paramLabel="FILE", description="path of the input FILE(s)")
          *     private File[] inputFiles;
          * }</pre>
          * <p>By default, the above gives a usage help message like the following:</p><pre>
          * Usage: &lt;main class&gt; [FILE...]
          * [FILE...]       path of the input FILE(s)
          * </pre>
          * @return name of the positional parameter used in the usage help message
          */
         String paramLabel() default "";
 
         /**
          * <p>
          * Optionally specify a {@code type} to control exactly what Class the positional parameter should be converted
          * to. This may be useful when the field type is an interface or an abstract class. For example, a field can
          * be declared to have type {@code java.lang.Number}, and annotating {@code @Parameters(type=Short.class)}
          * ensures that the positional parameter value is converted to a {@code Short} before setting the field value.
          * </p><p>
          * For array fields whose <em>component</em> type is an interface or abstract class, specify the concrete <em>component</em> type.
          * For example, a field with type {@code Number[]} may be annotated with {@code @Parameters(type=Short.class)}
          * to ensure that positional parameter values are converted to {@code Short} before adding an element to the array.
          * </p><p>
          * Picocli will use the {@link ITypeConverter} that is
          * {@linkplain #registerConverter(Class, ITypeConverter) registered} for the specified type to convert
          * the raw String values before modifying the field value.
          * </p><p>
          * Prior to 2.0, the {@code type} attribute was necessary for {@code Collection} and {@code Map} fields,
          * but starting from 2.0 picocli will infer the component type from the generic type's type arguments.
          * For example, for a field of type {@code Map<TimeUnit, Long>} picocli will know the positional parameter
          * should be split up in key=value pairs, where the key should be converted to a {@code java.util.concurrent.TimeUnit}
          * enum value, and the value should be converted to a {@code Long}. No {@code @Parameters(type=...)} type attribute
          * is required for this. For generic types with wildcards, picocli will take the specified upper or lower bound
          * as the Class to convert to, unless the {@code @Parameters} annotation specifies an explicit {@code type} attribute.
          * </p><p>
          * If the field type is a raw collection or a raw map, and you want it to contain other values than Strings,
          * or if the generic type's type arguments are interfaces or abstract classes, you may
          * specify a {@code type} attribute to control the Class that the positional parameter should be converted to.
          * @return the type(s) to convert the raw String values
          */
         Class<?>[] type() default {};
 
         /**
          * Specify a regular expression to use to split positional parameter values before applying them to the field.
          * All elements resulting from the split are added to the array or Collection. Ignored for single-value fields.
          * @return a regular expression to split operand values or {@code ""} if the value should not be split
          * @see String#split(String)
          */
         String split() default "";
 
         /**
          * Set {@code hidden=true} if this parameter should not be included in the usage message.
          * @return whether this parameter should be excluded from the usage message
          */
         boolean hidden() default false;
     }
 
     /**
      * <p>Annotate your class with {@code @Command} when you want more control over the format of the generated help
      * message.
      * </p><pre>
      * &#064;Command(name      = "Encrypt",
      *        description = "Encrypt FILE(s), or standard input, to standard output or to the output file.",
      *        footer      = "Copyright (c) 2017")
      * public class Encrypt {
      *     &#064;Parameters(paramLabel = "FILE", type = File.class, description = "Any number of input files")
      *     private List&lt;File&gt; files     = new ArrayList&lt;File&gt;();
      *
      *     &#064;Option(names = { "-o", "--out" }, description = "Output file (default: print to console)")
      *     private File outputFile;
      * }</pre>
      * <p>
      * The structure of a help message looks like this:
      * </p><ul>
      *   <li>[header]</li>
      *   <li>[synopsis]: {@code Usage: <commandName> [OPTIONS] [FILE...]}</li>
      *   <li>[description]</li>
      *   <li>[parameter list]: {@code      [FILE...]   Any number of input files}</li>
      *   <li>[option list]: {@code   -h, --help   prints this help message and exits}</li>
      *   <li>[footer]</li>
      * </ul> */
     @Retention(RetentionPolicy.RUNTIME)
     @Target({ElementType.TYPE, ElementType.LOCAL_VARIABLE, ElementType.PACKAGE})
     public @interface Command {
         /** Program name to show in the synopsis. If omitted, {@code "<main class>"} is used.
          * For {@linkplain #subcommands() declaratively added} subcommands, this attribute is also used
          * by the parser to recognize subcommands in the command line arguments.
          * @return the program name to show in the synopsis
          * @see Help#commandName */
         String name() default "<main class>";
 
         /** A list of classes to instantiate and register as subcommands. When registering subcommands declaratively
          * like this, you don't need to call the {@link CommandLine#addSubcommand(String, Object)} method. For example, this:
          * <pre>
          * &#064;Command(subcommands = {
          *         GitStatus.class,
          *         GitCommit.class,
          *         GitBranch.class })
          * public class Git { ... }
          *
          * CommandLine commandLine = new CommandLine(new Git());
          * </pre> is equivalent to this:
          * <pre>
          * // alternative: programmatically add subcommands.
          * // NOTE: in this case there should be no `subcommands` attribute on the @Command annotation.
          * &#064;Command public class Git { ... }
          *
          * CommandLine commandLine = new CommandLine(new Git())
          *         .addSubcommand("status",   new GitStatus())
          *         .addSubcommand("commit",   new GitCommit())
          *         .addSubcommand("branch",   new GitBranch());
          * </pre>
          * @return the declaratively registered subcommands of this command, or an empty array if none
          * @see CommandLine#addSubcommand(String, Object)
          * @since 0.9.8
          */
         Class<?>[] subcommands() default {};
 
         /** String that separates options from option parameters. Default is {@code "="}. Spaces are also accepted.
          * @return the string that separates options from option parameters, used both when parsing and when generating usage help
          * @see Help#separator
          * @see CommandLine#setSeparator(String) */
         String separator() default "=";
 
         /** Version information for this command, to print to the console when the user specifies an
          * {@linkplain Option#versionHelp() option} to request version help. This is not part of the usage help message.
          *
          * @return a string or an array of strings with version information about this command.
          * @since 0.9.8
          * @see CommandLine#printVersionHelp(PrintStream)
          */
         String[] version() default {};
 
         /** Set the heading preceding the header section. May contain embedded {@linkplain java.util.Formatter format specifiers}.
          * @return the heading preceding the header section
          * @see Help#headerHeading(Object...)  */
         String headerHeading() default "";
 
         /** Optional summary description of the command, shown before the synopsis.
          * @return summary description of the command
          * @see Help#header
          * @see Help#header(Object...)  */
         String[] header() default {};
 
         /** Set the heading preceding the synopsis text. May contain embedded
          * {@linkplain java.util.Formatter format specifiers}. The default heading is {@code "Usage: "} (without a line
          * break between the heading and the synopsis text).
          * @return the heading preceding the synopsis text
          * @see Help#synopsisHeading(Object...)  */
         String synopsisHeading() default "Usage: ";
 
         /** Specify {@code true} to generate an abbreviated synopsis like {@code "<main> [OPTIONS] [PARAMETERS...]"}.
          * By default, a detailed synopsis with individual option names and parameters is generated.
          * @return whether the synopsis should be abbreviated
          * @see Help#abbreviateSynopsis
          * @see Help#abbreviatedSynopsis()
          * @see Help#detailedSynopsis(Comparator, boolean) */
         boolean abbreviateSynopsis() default false;
 
         /** Specify one or more custom synopsis lines to display instead of an auto-generated synopsis.
          * @return custom synopsis text to replace the auto-generated synopsis
          * @see Help#customSynopsis
          * @see Help#customSynopsis(Object...) */
         String[] customSynopsis() default {};
 
         /** Set the heading preceding the description section. May contain embedded {@linkplain java.util.Formatter format specifiers}.
          * @return the heading preceding the description section
          * @see Help#descriptionHeading(Object...)  */
         String descriptionHeading() default "";
 
         /** Optional text to display between the synopsis line(s) and the list of options.
          * @return description of this command
          * @see Help#description
          * @see Help#description(Object...) */
         String[] description() default {};
 
         /** Set the heading preceding the parameters list. May contain embedded {@linkplain java.util.Formatter format specifiers}.
          * @return the heading preceding the parameters list
          * @see Help#parameterListHeading(Object...)  */
         String parameterListHeading() default "";
 
         /** Set the heading preceding the options list. May contain embedded {@linkplain java.util.Formatter format specifiers}.
          * @return the heading preceding the options list
          * @see Help#optionListHeading(Object...)  */
         String optionListHeading() default "";
 
         /** Specify {@code false} to show Options in declaration order. The default is to sort alphabetically.
          * @return whether options should be shown in alphabetic order.
          * @see Help#sortOptions */
         boolean sortOptions() default true;
 
         /** Prefix required options with this character in the options list. The default is no marker: the synopsis
          * indicates which options and parameters are required.
          * @return the character to show in the options list to mark required options
          * @see Help#requiredOptionMarker */
         char requiredOptionMarker() default ' ';
 
         /** Specify {@code true} to show default values in the description column of the options list (except for
          * boolean options). False by default.
          * @return whether the default values for options and parameters should be shown in the description column
          * @see Help#showDefaultValues */
         boolean showDefaultValues() default false;
 
         /** Set the heading preceding the subcommands list. May contain embedded {@linkplain java.util.Formatter format specifiers}.
          * The default heading is {@code "Commands:%n"} (with a line break at the end).
          * @return the heading preceding the subcommands list
          * @see Help#commandListHeading(Object...)  */
         String commandListHeading() default "Commands:%n";
 
         /** Set the heading preceding the footer section. May contain embedded {@linkplain java.util.Formatter format specifiers}.
          * @return the heading preceding the footer section
          * @see Help#footerHeading(Object...)  */
         String footerHeading() default "";
 
         /** Optional text to display after the list of options.
          * @return text to display after the list of options
          * @see Help#footer
          * @see Help#footer(Object...) */
         String[] footer() default {};
     }
     /**
      * <p>
      * When parsing command line arguments and initializing
      * fields annotated with {@link Option @Option} or {@link Parameters @Parameters},
      * String values can be converted to any type for which a {@code ITypeConverter} is registered.
      * </p><p>
      * This interface defines the contract for classes that know how to convert a String into some domain object.
      * Custom converters can be registered with the {@link #registerConverter(Class, ITypeConverter)} method.
      * </p><p>
      * Java 8 lambdas make it easy to register custom type converters:
      * </p>
      * <pre>
      * commandLine.registerConverter(java.nio.file.Path.class, s -&gt; java.nio.file.Paths.get(s));
      * commandLine.registerConverter(java.time.Duration.class, s -&gt; java.time.Duration.parse(s));</pre>
      * <p>
      * Built-in type converters are pre-registered for the following java 1.5 types:
      * </p>
      * <ul>
      *   <li>all primitive types</li>
      *   <li>all primitive wrapper types: Boolean, Byte, Character, Double, Float, Integer, Long, Short</li>
      *   <li>any enum</li>
      *   <li>java.io.File</li>
      *   <li>java.math.BigDecimal</li>
      *   <li>java.math.BigInteger</li>
      *   <li>java.net.InetAddress</li>
      *   <li>java.net.URI</li>
      *   <li>java.net.URL</li>
      *   <li>java.nio.charset.Charset</li>
      *   <li>java.sql.Time</li>
      *   <li>java.util.Date</li>
      *   <li>java.util.UUID</li>
      *   <li>java.util.regex.Pattern</li>
      *   <li>StringBuilder</li>
      *   <li>CharSequence</li>
      *   <li>String</li>
      * </ul>
      * @param <K> the type of the object that is the result of the conversion
      */
     public interface ITypeConverter<K> {
         /**
          * Converts the specified command line argument value to some domain object.
          * @param value the command line argument String value
          * @return the resulting domain object
          * @throws Exception an exception detailing what went wrong during the conversion
          */
         K convert(String value) throws Exception;
     }
     /** Describes the number of parameters required and accepted by an option or a positional parameter.
      * @since 0.9.7
      */
     public static class Range implements Comparable<Range> {
         /** Required number of parameters for an option or positional parameter. */
         public final int min;
         /** Maximum accepted number of parameters for an option or positional parameter. */
         public final int max;
         public final boolean isVariable;
         private final boolean isUnspecified;
         private final String originalValue;
 
         /** Constructs a new Range object with the specified parameters.
          * @param min minimum number of required parameters
          * @param max maximum number of allowed parameters (or Integer.MAX_VALUE if variable)
          * @param variable {@code true} if any number or parameters is allowed, {@code false} otherwise
          * @param unspecified {@code true} if no arity was specified on the option/parameter (value is based on type)
          * @param originalValue the original value that was specified on the option or parameter
          */
         public Range(int min, int max, boolean variable, boolean unspecified, String originalValue) {
             this.min = min;
             this.max = max;
             this.isVariable = variable;
             this.isUnspecified = unspecified;
             this.originalValue = originalValue;
         }
         /** Returns a new {@code Range} based on the {@link Option#arity()} annotation on the specified field,
          * or the field type's default arity if no arity was specified.
          * @param field the field whose Option annotation to inspect
          * @return a new {@code Range} based on the Option arity annotation on the specified field */
         public static Range optionArity(Field field) {
             return field.isAnnotationPresent(Option.class)
                     ? adjustForType(Range.valueOf(field.getAnnotation(Option.class).arity()), field)
                     : new Range(0, 0, false, true, "0");
         }
         /** Returns a new {@code Range} based on the {@link Parameters#arity()} annotation on the specified field,
          * or the field type's default arity if no arity was specified.
          * @param field the field whose Parameters annotation to inspect
          * @return a new {@code Range} based on the Parameters arity annotation on the specified field */
         public static Range parameterArity(Field field) {
             return field.isAnnotationPresent(Parameters.class)
                     ? adjustForType(Range.valueOf(field.getAnnotation(Parameters.class).arity()), field)
                     : new Range(0, 0, false, true, "0");
         }
         /** Returns a new {@code Range} based on the {@link Parameters#index()} annotation on the specified field.
          * @param field the field whose Parameters annotation to inspect
          * @return a new {@code Range} based on the Parameters index annotation on the specified field */
         public static Range parameterIndex(Field field) {
             return field.isAnnotationPresent(Parameters.class)
                     ? Range.valueOf(field.getAnnotation(Parameters.class).index())
                     : new Range(0, 0, false, true, "0");
         }
         static Range adjustForType(Range result, Field field) {
             return result.isUnspecified ? defaultArity(field) : result;
         }
         /** Returns the default arity {@code Range}: for {@link Option options} this is 0 for booleans and 1 for
          * other types, for {@link Parameters parameters} booleans have arity 0, arrays or Collections have
          * arity "0..*", and other types have arity 1.
          * @param field the field whose default arity to return
          * @return a new {@code Range} indicating the default arity of the specified field
          * @since 2.0 */
         public static Range defaultArity(Field field) {
             Class<?> type = field.getType();
             if (field.isAnnotationPresent(Option.class)) {
                 return defaultArity(type);
             }
             if (isMultiValue(type)) {
                 return Range.valueOf("0..1");
             }
             return Range.valueOf("1");// for single-valued fields (incl. boolean positional parameters)
         }
         /** Returns the default arity {@code Range} for {@link Option options}: booleans have arity 0, other types have arity 1.
          * @param type the type whose default arity to return
          * @return a new {@code Range} indicating the default arity of the specified type */
         public static Range defaultArity(Class<?> type) {
             return isBoolean(type) ? Range.valueOf("0") : Range.valueOf("1");
         }
         private int size() { return 1 + max - min; }
         static Range parameterCapacity(Field field) {
             Range arity = parameterArity(field);
             if (!isMultiValue(field)) { return arity; }
             Range index = parameterIndex(field);
             if (arity.max == 0)    { return arity; }
             if (index.size() == 1) { return arity; }
             if (index.isVariable)  { return Range.valueOf(arity.min + "..*"); }
             if (arity.size() == 1) { return Range.valueOf(arity.min * index.size() + ""); }
             if (arity.isVariable)  { return Range.valueOf(arity.min * index.size() + "..*"); }
             return Range.valueOf(arity.min * index.size() + ".." + arity.max * index.size());
         }
         /** Leniently parses the specified String as an {@code Range} value and return the result. A range string can
          * be a fixed integer value or a range of the form {@code MIN_VALUE + ".." + MAX_VALUE}. If the
          * {@code MIN_VALUE} string is not numeric, the minimum is zero. If the {@code MAX_VALUE} is not numeric, the
          * range is taken to be variable and the maximum is {@code Integer.MAX_VALUE}.
          * @param range the value range string to parse
          * @return a new {@code Range} value */
         public static Range valueOf(String range) {
             range = range.trim();
             boolean unspecified = range.length() == 0 || range.startsWith(".."); // || range.endsWith("..");
             int min = -1, max = -1;
             boolean variable = false;
             int dots = -1;
             if ((dots = range.indexOf("..")) >= 0) {
                 min = parseInt(range.substring(0, dots), 0);
                 max = parseInt(range.substring(dots + 2), Integer.MAX_VALUE);
                 variable = max == Integer.MAX_VALUE;
             } else {
                 max = parseInt(range, Integer.MAX_VALUE);
                 variable = max == Integer.MAX_VALUE;
                 min = variable ? 0 : max;
             }
             Range result = new Range(min, max, variable, unspecified, range);
             return result;
         }
         private static int parseInt(String str, int defaultValue) {
             try {
                 return Integer.parseInt(str);
             } catch (Exception ex) {
                 return defaultValue;
             }
         }
         /** Returns a new Range object with the {@code min} value replaced by the specified value.
          * The {@code max} of the returned Range is guaranteed not to be less than the new {@code min} value.
          * @param newMin the {@code min} value of the returned Range object
          * @return a new Range object with the specified {@code min} value */
         public Range min(int newMin) { return new Range(newMin, Math.max(newMin, max), isVariable, isUnspecified, originalValue); }
 
         /** Returns a new Range object with the {@code max} value replaced by the specified value.
          * The {@code min} of the returned Range is guaranteed not to be greater than the new {@code max} value.
          * @param newMax the {@code max} value of the returned Range object
          * @return a new Range object with the specified {@code max} value */
         public Range max(int newMax) { return new Range(Math.min(min, newMax), newMax, isVariable, isUnspecified, originalValue); }
 
         /**
          * Returns {@code true} if this Range includes the specified value, {@code false} otherwise.
          * @param value the value to check
          * @return {@code true} if the specified value is not less than the minimum and not greater than the maximum of this Range
          */
         public boolean contains(int value) { return min <= value && max >= value; }
 
         public boolean equals(Object object) {
             if (!(object instanceof Range)) { return false; }
             Range other = (Range) object;
             return other.max == this.max && other.min == this.min && other.isVariable == this.isVariable;
         }
         public int hashCode() {
             return ((17 * 37 + max) * 37 + min) * 37 + (isVariable ? 1 : 0);
         }
         public String toString() {
             return min == max ? String.valueOf(min) : min + ".." + (isVariable ? "*" : max);
         }
         public int compareTo(Range other) {
             int result = min - other.min;
             return (result == 0) ? max - other.max : result;
         }
     }
     static void init(Class<?> cls,
                               List<Field> requiredFields,
                               Map<String, Field> optionName2Field,
                               Map<Character, Field> singleCharOption2Field,
                               List<Field> positionalParametersFields) {
         Field[] declaredFields = cls.getDeclaredFields();
         for (Field field : declaredFields) {
             field.setAccessible(true);
             if (field.isAnnotationPresent(Option.class)) {
                 Option option = field.getAnnotation(Option.class);
                 if (option.required()) {
                     requiredFields.add(field);
                 }
                 for (String name : option.names()) { // cannot be null or empty
                     Field existing = optionName2Field.put(name, field);
                     if (existing != null && existing != field) {
                         throw DuplicateOptionAnnotationsException.create(name, field, existing);
                     }
                     if (name.length() == 2 && name.startsWith("-")) {
                         char flag = name.charAt(1);
                         Field existing2 = singleCharOption2Field.put(flag, field);
                         if (existing2 != null && existing2 != field) {
                             throw DuplicateOptionAnnotationsException.create(name, field, existing2);
                         }
                     }
                 }
             }
             if (field.isAnnotationPresent(Parameters.class)) {
                 if (field.isAnnotationPresent(Option.class)) {
                     throw new DuplicateOptionAnnotationsException("A field can be either @Option or @Parameters, but '"
                             + field.getName() + "' is both.");
                 }
                 positionalParametersFields.add(field);
                 Range arity = Range.parameterArity(field);
                 if (arity.min > 0) {
                     requiredFields.add(field);
                 }
             }
         }
     }
     static void validatePositionalParameters(List<Field> positionalParametersFields) {
         int min = 0;
         for (Field field : positionalParametersFields) {
             Range index = Range.parameterIndex(field);
             if (index.min > min) {
                 throw new ParameterIndexGapException("Missing field annotated with @Parameter(index=" + min +
                         "). Nearest field '" + field.getName() + "' has index=" + index.min);
             }
             min = Math.max(min, index.max);
             min = min == Integer.MAX_VALUE ? min : min + 1;
         }
     }
     private static <T> Stack<T> reverse(Stack<T> stack) {
         Collections.reverse(stack);
         return stack;
     }
     /**
      * Helper class responsible for processing command line arguments.
      */
     private class Interpreter {
         private final Map<String, CommandLine> commands                  = new LinkedHashMap<String, CommandLine>();
         private final Map<Class<?>, ITypeConverter<?>> converterRegistry = new HashMap<Class<?>, ITypeConverter<?>>();
         private final Map<String, Field> optionName2Field                = new HashMap<String, Field>();
         private final Map<Character, Field> singleCharOption2Field       = new HashMap<Character, Field>();
         private final List<Field> requiredFields                         = new ArrayList<Field>();
         private final List<Field> positionalParametersFields             = new ArrayList<Field>();
         private final Object command;
         private boolean isHelpRequested;
         private String separator = Help.DEFAULT_SEPARATOR;
         private int position;
 
         Interpreter(Object command) {
             converterRegistry.put(Path.class,          new BuiltIn.PathConverter());
             converterRegistry.put(Object.class,        new BuiltIn.StringConverter());
             converterRegistry.put(String.class,        new BuiltIn.StringConverter());
             converterRegistry.put(StringBuilder.class, new BuiltIn.StringBuilderConverter());
             converterRegistry.put(CharSequence.class,  new BuiltIn.CharSequenceConverter());
             converterRegistry.put(Byte.class,          new BuiltIn.ByteConverter());
             converterRegistry.put(Byte.TYPE,           new BuiltIn.ByteConverter());
             converterRegistry.put(Boolean.class,       new BuiltIn.BooleanConverter());
             converterRegistry.put(Boolean.TYPE,        new BuiltIn.BooleanConverter());
             converterRegistry.put(Character.class,     new BuiltIn.CharacterConverter());
             converterRegistry.put(Character.TYPE,      new BuiltIn.CharacterConverter());
             converterRegistry.put(Short.class,         new BuiltIn.ShortConverter());
             converterRegistry.put(Short.TYPE,          new BuiltIn.ShortConverter());
             converterRegistry.put(Integer.class,       new BuiltIn.IntegerConverter());
             converterRegistry.put(Integer.TYPE,        new BuiltIn.IntegerConverter());
             converterRegistry.put(Long.class,          new BuiltIn.LongConverter());
             converterRegistry.put(Long.TYPE,           new BuiltIn.LongConverter());
             converterRegistry.put(Float.class,         new BuiltIn.FloatConverter());
             converterRegistry.put(Float.TYPE,          new BuiltIn.FloatConverter());
             converterRegistry.put(Double.class,        new BuiltIn.DoubleConverter());
             converterRegistry.put(Double.TYPE,         new BuiltIn.DoubleConverter());
             converterRegistry.put(File.class,          new BuiltIn.FileConverter());
             converterRegistry.put(URI.class,           new BuiltIn.URIConverter());
             converterRegistry.put(URL.class,           new BuiltIn.URLConverter());
             converterRegistry.put(Date.class,          new BuiltIn.ISO8601DateConverter());
             converterRegistry.put(Time.class,          new BuiltIn.ISO8601TimeConverter());
             converterRegistry.put(BigDecimal.class,    new BuiltIn.BigDecimalConverter());
             converterRegistry.put(BigInteger.class,    new BuiltIn.BigIntegerConverter());
             converterRegistry.put(Charset.class,       new BuiltIn.CharsetConverter());
             converterRegistry.put(InetAddress.class,   new BuiltIn.InetAddressConverter());
             converterRegistry.put(Pattern.class,       new BuiltIn.PatternConverter());
             converterRegistry.put(UUID.class,          new BuiltIn.UUIDConverter());
 
             this.command                 = Assert.notNull(command, "command");
             Class<?> cls                 = command.getClass();
             String declaredName          = null;
             String declaredSeparator     = null;
             boolean hasCommandAnnotation = false;
             while (cls != null) {
                 init(cls, requiredFields, optionName2Field, singleCharOption2Field, positionalParametersFields);
                 if (cls.isAnnotationPresent(Command.class)) {
                     hasCommandAnnotation = true;
                     Command cmd = cls.getAnnotation(Command.class);
                     declaredSeparator = (declaredSeparator == null) ? cmd.separator() : declaredSeparator;
                     declaredName = (declaredName == null) ? cmd.name() : declaredName;
                     CommandLine.this.versionLines.addAll(Arrays.asList(cmd.version()));
 
                     for (Class<?> sub : cmd.subcommands()) {
                         Command subCommand = sub.getAnnotation(Command.class);
                         if (subCommand == null || Help.DEFAULT_COMMAND_NAME.equals(subCommand.name())) {
                             throw new InitializationException("Subcommand " + sub.getName() +
                                     " is missing the mandatory @Command annotation with a 'name' attribute");
                         }
                         try {
                             Constructor<?> constructor = sub.getDeclaredConstructor();
                             constructor.setAccessible(true);
                             CommandLine commandLine = toCommandLine(constructor.newInstance());
                             commandLine.parent = CommandLine.this;
                             commands.put(subCommand.name(), commandLine);
                         }
                         catch (InitializationException ex) { throw ex; }
                         catch (NoSuchMethodException ex) { throw new InitializationException("Cannot instantiate subcommand " +
                                 sub.getName() + ": the class has no constructor", ex); }
                         catch (Exception ex) {
                             throw new InitializationException("Could not instantiate and add subcommand " +
                                     sub.getName() + ": " + ex, ex);
                         }
                     }
                 }
                 cls = cls.getSuperclass();
             }
             separator = declaredSeparator != null ? declaredSeparator : separator;
             CommandLine.this.commandName = declaredName != null ? declaredName : CommandLine.this.commandName;
             Collections.sort(positionalParametersFields, new PositionalParametersSorter());
             validatePositionalParameters(positionalParametersFields);
 
             if (positionalParametersFields.isEmpty() && optionName2Field.isEmpty() && !hasCommandAnnotation) {
                 throw new InitializationException(command + " (" + command.getClass() +
                         ") is not a command: it has no @Command, @Option or @Parameters annotations");
             }
         }
 
         /**
          * Entry point into parsing command line arguments.
          * @param args the command line arguments
          * @return a list with all commands and subcommands initialized by this method
          * @throws ParameterException if the specified command line arguments are invalid
          */
         List<CommandLine> parse(String... args) {
             Assert.notNull(args, "argument array");
             if (tracer.isInfo()) {tracer.info("Parsing %d command line args %s%n", args.length, Arrays.toString(args));}
             Stack<String> arguments = new Stack<String>();
             for (int i = args.length - 1; i >= 0; i--) {
                 arguments.push(args[i]);
             }
             List<CommandLine> result = new ArrayList<CommandLine>();
             parse(result, arguments, args);
             return result;
         }
 
         private void parse(List<CommandLine> parsedCommands, Stack<String> argumentStack, String[] originalArgs) {
             // first reset any state in case this CommandLine instance is being reused
             isHelpRequested = false;
             CommandLine.this.versionHelpRequested = false;
             CommandLine.this.usageHelpRequested = false;
 
             Class<?> cmdClass = this.command.getClass();
             if (tracer.isDebug()) {tracer.debug("Initializing %s: %d options, %d positional parameters, %d required, %d subcommands.%n", cmdClass.getName(), new HashSet<Field>(optionName2Field.values()).size(), positionalParametersFields.size(), requiredFields.size(), commands.size());}
             parsedCommands.add(CommandLine.this);
             List<Field> required = new ArrayList<Field>(requiredFields);
             Set<Field> initialized = new HashSet<Field>();
             Collections.sort(required, new PositionalParametersSorter());
             try {
                 processArguments(parsedCommands, argumentStack, required, initialized, originalArgs);
             } catch (ParameterException ex) {
                 throw ex;
             } catch (Exception ex) {
                 int offendingArgIndex = originalArgs.length - argumentStack.size() - 1;
                 String arg = offendingArgIndex >= 0 && offendingArgIndex < originalArgs.length ? originalArgs[offendingArgIndex] : "?";
                 throw ParameterException.create(CommandLine.this, ex, arg, offendingArgIndex, originalArgs);
             }
             if (!isAnyHelpRequested() && !required.isEmpty()) {
                 for (Field missing : required) {
                     if (missing.isAnnotationPresent(Option.class)) {
                         throw MissingParameterException.create(CommandLine.this, required, separator);
                     } else {
                         assertNoMissingParameters(missing, Range.parameterArity(missing).min, argumentStack);
                     }
                 }
             }
             if (!unmatchedArguments.isEmpty()) {
                 if (!isUnmatchedArgumentsAllowed()) { throw new UnmatchedArgumentException(CommandLine.this, unmatchedArguments); }
                 if (tracer.isWarn()) { tracer.warn("Unmatched arguments: %s%n", unmatchedArguments); }
             }
         }
 
         private void processArguments(List<CommandLine> parsedCommands,
                                       Stack<String> args,
                                       Collection<Field> required,
                                       Set<Field> initialized,
                                       String[] originalArgs) throws Exception {
             // arg must be one of:
             // 1. the "--" double dash separating options from positional arguments
             // 1. a stand-alone flag, like "-v" or "--verbose": no value required, must map to boolean or Boolean field
             // 2. a short option followed by an argument, like "-f file" or "-ffile": may map to any type of field
             // 3. a long option followed by an argument, like "-file out.txt" or "-file=out.txt"
             // 3. one or more remaining arguments without any associated options. Must be the last in the list.
             // 4. a combination of stand-alone options, like "-vxr". Equivalent to "-v -x -r", "-v true -x true -r true"
             // 5. a combination of stand-alone options and one option with an argument, like "-vxrffile"
 
             while (!args.isEmpty()) {
                 String arg = args.pop();
                 if (tracer.isDebug()) {tracer.debug("Processing argument '%s'. Remainder=%s%n", arg, reverse((Stack<String>) args.clone()));}
 
                 // Double-dash separates options from positional arguments.
                 // If found, then interpret the remaining args as positional parameters.
                 if ("--".equals(arg)) {
                     tracer.info("Found end-of-options delimiter '--'. Treating remainder as positional parameters.%n");
                     processRemainderAsPositionalParameters(required, initialized, args);
                     return; // we are done
                 }
 
                 // if we find another command, we are done with the current command
                 if (commands.containsKey(arg)) {
                     if (!isHelpRequested && !required.isEmpty()) { // ensure current command portion is valid
                         throw MissingParameterException.create(CommandLine.this, required, separator);
                     }
                     if (tracer.isDebug()) {tracer.debug("Found subcommand '%s' (%s)%n", arg, commands.get(arg).interpreter.command.getClass().getName());}
                     commands.get(arg).interpreter.parse(parsedCommands, args, originalArgs);
                     return; // remainder done by the command
                 }
 
                 // First try to interpret the argument as a single option (as opposed to a compact group of options).
                 // A single option may be without option parameters, like "-v" or "--verbose" (a boolean value),
                 // or an option may have one or more option parameters.
                 // A parameter may be attached to the option.
                 boolean paramAttachedToOption = false;
                 int separatorIndex = arg.indexOf(separator);
                 if (separatorIndex > 0) {
                     String key = arg.substring(0, separatorIndex);
                     // be greedy. Consume the whole arg as an option if possible.
                     if (optionName2Field.containsKey(key) && !optionName2Field.containsKey(arg)) {
                         paramAttachedToOption = true;
                         String optionParam = arg.substring(separatorIndex + separator.length());
                         args.push(optionParam);
                         arg = key;
                         if (tracer.isDebug()) {tracer.debug("Separated '%s' option from '%s' option parameter%n", key, optionParam);}
                     } else {
                         if (tracer.isDebug()) {tracer.debug("'%s' contains separator '%s' but '%s' is not a known option%n", arg, separator, key);}
                     }
                 } else {
                     if (tracer.isDebug()) {tracer.debug("'%s' cannot be separated into <option>%s<option-parameter>%n", arg, separator);}
                 }
                 if (optionName2Field.containsKey(arg)) {
                     processStandaloneOption(required, initialized, arg, args, paramAttachedToOption);
                 }
                 // Compact (single-letter) options can be grouped with other options or with an argument.
                 // only single-letter options can be combined with other options or with an argument
                 else if (arg.length() > 2 && arg.startsWith("-")) {
                     if (tracer.isDebug()) {tracer.debug("Trying to process '%s' as clustered short options%n", arg, args);}
                     processClusteredShortOptions(required, initialized, arg, args);
                 }
                 // The argument could not be interpreted as an option.
                 // We take this to mean that the remainder are positional arguments
                 else {
                     args.push(arg);
                     if (tracer.isDebug()) {tracer.debug("Could not find option '%s', deciding whether to treat as unmatched option or positional parameter...%n", arg);}
                     if (resemblesOption(arg)) { handleUnmatchedArguments(args.pop()); continue; } // #149
                     if (tracer.isDebug()) {tracer.debug("No option named '%s' found. Processing remainder as positional parameters%n", arg);}
                     processPositionalParameter(required, initialized, args);
                 }
             }
         }
         private boolean resemblesOption(String arg) {
             int count = 0;
             for (String optionName : optionName2Field.keySet()) {
                 for (int i = 0; i < arg.length(); i++) {
                     if (optionName.length() > i && arg.charAt(i) == optionName.charAt(i)) { count++; } else { break; }
                 }
             }
             boolean result = count > 0 && count * 10 >= optionName2Field.size() * 9; // at least one prefix char in common with 9 out of 10 options
             if (tracer.isDebug()) {tracer.debug("%s %s an option: %d matching prefix chars out of %d option names%n", arg, (result ? "resembles" : "doesn't resemble"), count, optionName2Field.size());}
             return result;
         }
         private void handleUnmatchedArguments(String arg) {Stack<String> args = new Stack<String>(); args.add(arg); handleUnmatchedArguments(args);}
         private void handleUnmatchedArguments(Stack<String> args) {
             while (!args.isEmpty()) { unmatchedArguments.add(args.pop()); } // addAll would give args in reverse order
         }
 
         private void processRemainderAsPositionalParameters(Collection<Field> required, Set<Field> initialized, Stack<String> args) throws Exception {
             while (!args.empty()) {
                 processPositionalParameter(required, initialized, args);
             }
         }
         private void processPositionalParameter(Collection<Field> required, Set<Field> initialized, Stack<String> args) throws Exception {
             if (tracer.isDebug()) {tracer.debug("Processing next arg as a positional parameter at index=%d. Remainder=%s%n", position, reverse((Stack<String>) args.clone()));}
             int consumed = 0;
             for (Field positionalParam : positionalParametersFields) {
                 Range indexRange = Range.parameterIndex(positionalParam);
                 if (!indexRange.contains(position)) {
                     continue;
                 }
                 @SuppressWarnings("unchecked")
                 Stack<String> argsCopy = (Stack<String>) args.clone();
                 Range arity = Range.parameterArity(positionalParam);
                 if (tracer.isDebug()) {tracer.debug("Position %d is in index range %s. Trying to assign args to %s, arity=%s%n", position, indexRange, positionalParam, arity);}
                 assertNoMissingParameters(positionalParam, arity.min, argsCopy);
                 int originalSize = argsCopy.size();
                 applyOption(positionalParam, Parameters.class, arity, false, argsCopy, initialized, "args[" + indexRange + "] at position " + position);
                 int count = originalSize - argsCopy.size();
                 if (count > 0) { required.remove(positionalParam); }
                 consumed = Math.max(consumed, count);
             }
             // remove processed args from the stack
             for (int i = 0; i < consumed; i++) { args.pop(); }
             position += consumed;
             if (tracer.isDebug()) {tracer.debug("Consumed %d arguments, moving position to index %d.%n", consumed, position);}
             if (consumed == 0 && !args.isEmpty()) {
                 handleUnmatchedArguments(args.pop());
             }
         }
 
         private void processStandaloneOption(Collection<Field> required,
                                              Set<Field> initialized,
                                              String arg,
                                              Stack<String> args,
                                              boolean paramAttachedToKey) throws Exception {
             Field field = optionName2Field.get(arg);
             required.remove(field);
             Range arity = Range.optionArity(field);
             if (paramAttachedToKey) {
                 arity = arity.min(Math.max(1, arity.min)); // if key=value, minimum arity is at least 1
             }
             if (tracer.isDebug()) {tracer.debug("Found option named '%s': field %s, arity=%s%n", arg, field, arity);}
             applyOption(field, Option.class, arity, paramAttachedToKey, args, initialized, "option " + arg);
         }
 
         private void processClusteredShortOptions(Collection<Field> required,
                                                   Set<Field> initialized,
                                                   String arg,
                                                   Stack<String> args)
                 throws Exception {
             String prefix = arg.substring(0, 1);
             String cluster = arg.substring(1);
             boolean paramAttachedToOption = true;
             do {
                 if (cluster.length() > 0 && singleCharOption2Field.containsKey(cluster.charAt(0))) {
                     Field field = singleCharOption2Field.get(cluster.charAt(0));
                     Range arity = Range.optionArity(field);
                     String argDescription = "option " + prefix + cluster.charAt(0);
                     if (tracer.isDebug()) {tracer.debug("Found option '%s%s' in %s: field %s, arity=%s%n", prefix, cluster.charAt(0), arg, field, arity);}
                     required.remove(field);
                     cluster = cluster.length() > 0 ? cluster.substring(1) : "";
                     paramAttachedToOption = cluster.length() > 0;
                     if (cluster.startsWith(separator)) {// attached with separator, like -f=FILE or -v=true
                         cluster = cluster.substring(separator.length());
                         arity = arity.min(Math.max(1, arity.min)); // if key=value, minimum arity is at least 1
                     }
                     if (arity.min > 0 && !empty(cluster)) {
                         if (tracer.isDebug()) {tracer.debug("Trying to process '%s' as option parameter%n", cluster);}
                     }
                     // arity may be >= 1, or
                     // arity <= 0 && !cluster.startsWith(separator)
                     // e.g., boolean @Option("-v", arity=0, varargs=true); arg "-rvTRUE", remainder cluster="TRUE"
                     if (!empty(cluster)) {
                         args.push(cluster); // interpret remainder as option parameter
                     }
                     int consumed = applyOption(field, Option.class, arity, paramAttachedToOption, args, initialized, argDescription);
                     // only return if cluster (and maybe more) was consumed, otherwise continue do-while loop
                     if (empty(cluster) || consumed > 0 || args.isEmpty()) {
                         return;
                     }
                     cluster = args.pop();
                 } else { // cluster is empty || cluster.charAt(0) is not a short option key
                     if (cluster.length() == 0) { // we finished parsing a group of short options like -rxv
                         return; // return normally and parse the next arg
                     }
                     // We get here when the remainder of the cluster group is neither an option,
                     // nor a parameter that the last option could consume.
                     if (arg.endsWith(cluster)) {
                         args.push(paramAttachedToOption ? prefix + cluster : cluster);
                         if (args.peek().equals(arg)) { // #149 be consistent between unmatched short and long options
                             if (tracer.isDebug()) {tracer.debug("Could not match any short options in %s, deciding whether to treat as unmatched option or positional parameter...%n", arg);}
                             if (resemblesOption(arg)) { handleUnmatchedArguments(args.pop()); return; } // #149
                             processPositionalParameter(required, initialized, args);
                             return;
                         }
                         // remainder was part of a clustered group that could not be completely parsed
                         if (tracer.isDebug()) {tracer.debug("No option found for %s in %s%n", cluster, arg);}
                         handleUnmatchedArguments(args.pop());
                     } else {
                         args.push(cluster);
                         if (tracer.isDebug()) {tracer.debug("%s is not an option parameter for %s%n", cluster, arg);}
                         processPositionalParameter(required, initialized, args);
                     }
                     return;
                 }
             } while (true);
         }
 
         private int applyOption(Field field,
                                 Class<?> annotation,
                                 Range arity,
                                 boolean valueAttachedToOption,
                                 Stack<String> args,
                                 Set<Field> initialized,
                                 String argDescription) throws Exception {
             updateHelpRequested(field);
             int length = args.size();
             assertNoMissingParameters(field, arity.min, args);
 
             Class<?> cls = field.getType();
             if (cls.isArray()) {
                 return applyValuesToArrayField(field, annotation, arity, args, cls, argDescription);
             }
             if (Collection.class.isAssignableFrom(cls)) {
                 return applyValuesToCollectionField(field, annotation, arity, args, cls, argDescription);
             }
             if (Map.class.isAssignableFrom(cls)) {
                 return applyValuesToMapField(field, annotation, arity, args, cls, argDescription);
             }
             cls = getTypeAttribute(field)[0]; // field may be interface/abstract type, use annotation to get concrete type
             return applyValueToSingleValuedField(field, arity, args, cls, initialized, argDescription);
         }
 
         private int applyValueToSingleValuedField(Field field,
                                                   Range arity,
                                                   Stack<String> args,
                                                   Class<?> cls,
                                                   Set<Field> initialized,
                                                   String argDescription) throws Exception {
             boolean noMoreValues = args.isEmpty();
             String value = args.isEmpty() ? null : trim(args.pop()); // unquote the value
             int result = arity.min; // the number or args we need to consume
 
             // special logic for booleans: BooleanConverter accepts only "true" or "false".
             if ((cls == Boolean.class || cls == Boolean.TYPE) && arity.min <= 0) {
 
                 // boolean option with arity = 0..1 or 0..*: value MAY be a param
                 if (arity.max > 0 && ("true".equalsIgnoreCase(value) || "false".equalsIgnoreCase(value))) {
                     result = 1;            // if it is a varargs we only consume 1 argument if it is a boolean value
                 } else {
                     if (value != null) {
                         args.push(value); // we don't consume the value
                     }
                     Boolean currentValue = (Boolean) field.get(command);
                     value = String.valueOf(currentValue == null ? true : !currentValue); // #147 toggle existing boolean value
                 }
             }
             if (noMoreValues && value == null) {
                 return 0;
             }
             ITypeConverter<?> converter = getTypeConverter(cls, field);
             Object newValue = tryConvert(field, -1, converter, value, cls);
             Object oldValue = field.get(command);
             TraceLevel level = TraceLevel.INFO;
             String traceMessage = "Setting %s field '%s.%s' to '%5$s' (was '%4$s') for %6$s%n";
             if (initialized != null) {
                 if (initialized.contains(field)) {
                     if (!isOverwrittenOptionsAllowed()) {
                         throw new OverwrittenOptionException(CommandLine.this, optionDescription("", field, 0) +  " should be specified only once");
                     }
                     level = TraceLevel.WARN;
                     traceMessage = "Overwriting %s field '%s.%s' value '%s' with '%s' for %s%n";
                 }
                 initialized.add(field);
             }
             if (tracer.level.isEnabled(level)) { level.print(tracer, traceMessage, field.getType().getSimpleName(),
                         field.getDeclaringClass().getSimpleName(), field.getName(), String.valueOf(oldValue), String.valueOf(newValue), argDescription);
             }
             field.set(command, newValue);
             return result;
         }
         private int applyValuesToMapField(Field field,
                                           Class<?> annotation,
                                           Range arity,
                                           Stack<String> args,
                                           Class<?> cls,
                                           String argDescription) throws Exception {
             Class<?>[] classes = getTypeAttribute(field);
             if (classes.length < 2) { throw new ParameterException(CommandLine.this, "Field " + field + " needs two types (one for the map key, one for the value) but only has " + classes.length + " types configured."); }
             ITypeConverter<?> keyConverter   = getTypeConverter(classes[0], field);
             ITypeConverter<?> valueConverter = getTypeConverter(classes[1], field);
             Map<Object, Object> result = (Map<Object, Object>) field.get(command);
             if (result == null) {
                 result = createMap(cls);
                 field.set(command, result);
             }
             int originalSize = result.size();
             consumeMapArguments(field, arity, args, classes, keyConverter, valueConverter, result, argDescription);
             return result.size() - originalSize;
         }
 
         private void consumeMapArguments(Field field,
                                          Range arity,
                                          Stack<String> args,
                                          Class<?>[] classes,
                                          ITypeConverter<?> keyConverter,
                                          ITypeConverter<?> valueConverter,
                                          Map<Object, Object> result,
                                          String argDescription) throws Exception {
             // first do the arity.min mandatory parameters
             for (int i = 0; i < arity.min; i++) {
                 consumeOneMapArgument(field, arity, args, classes, keyConverter, valueConverter, result, i, argDescription);
             }
             // now process the varargs if any
             for (int i = arity.min; i < arity.max && !args.isEmpty(); i++) {
                 if (!field.isAnnotationPresent(Parameters.class)) {
                     if (commands.containsKey(args.peek()) || isOption(args.peek())) {
                         return;
                     }
                 }
                 consumeOneMapArgument(field, arity, args, classes, keyConverter, valueConverter, result, i, argDescription);
             }
         }
 
         private void consumeOneMapArgument(Field field,
                                            Range arity,
                                            Stack<String> args,
                                            Class<?>[] classes,
                                            ITypeConverter<?> keyConverter, ITypeConverter<?> valueConverter,
                                            Map<Object, Object> result,
                                            int index,
                                            String argDescription) throws Exception {
             String[] values = split(trim(args.pop()), field);
             for (String value : values) {
                 String[] keyValue = value.split("=");
                 if (keyValue.length < 2) {
                     String splitRegex = splitRegex(field);
                     if (splitRegex.length() == 0) {
                         throw new ParameterException(CommandLine.this, "Value for option " + optionDescription("", field,
                                 0) + " should be in KEY=VALUE format but was " + value);
                     } else {
                         throw new ParameterException(CommandLine.this, "Value for option " + optionDescription("", field,
                                 0) + " should be in KEY=VALUE[" + splitRegex + "KEY=VALUE]... format but was " + value);
                     }
                 }
                 Object mapKey =   tryConvert(field, index, keyConverter,   keyValue[0], classes[0]);
                 Object mapValue = tryConvert(field, index, valueConverter, keyValue[1], classes[1]);
                 result.put(mapKey, mapValue);
                 if (tracer.isInfo()) {tracer.info("Putting [%s : %s] in %s<%s, %s> field '%s.%s' for %s%n", String.valueOf(mapKey), String.valueOf(mapValue),
                         result.getClass().getSimpleName(), classes[0].getSimpleName(), classes[1].getSimpleName(), field.getDeclaringClass().getSimpleName(), field.getName(), argDescription);}
             }
         }
 
         private void checkMaxArityExceeded(Range arity, int remainder, Field field, String[] values) {
             if (values.length <= remainder) { return; }
             String desc = arity.max == remainder ? "" + remainder : arity + ", remainder=" + remainder;
             throw new MaxValuesforFieldExceededException(CommandLine.this, optionDescription("", field, -1) +
                     " max number of values (" + arity.max + ") exceeded: remainder is " + remainder + " but " +
                     values.length + " values were specified: " + Arrays.toString(values));
         }
 
         private int applyValuesToArrayField(Field field,
                                             Class<?> annotation,
                                             Range arity,
                                             Stack<String> args,
                                             Class<?> cls,
                                             String argDescription) throws Exception {
             Object existing = field.get(command);
             int length = existing == null ? 0 : Array.getLength(existing);
             Class<?> type = getTypeAttribute(field)[0];
             List<Object> converted = consumeArguments(field, annotation, arity, args, type, length, argDescription);
             List<Object> newValues = new ArrayList<Object>();
             for (int i = 0; i < length; i++) {
                 newValues.add(Array.get(existing, i));
             }
             for (Object obj : converted) {
                 if (obj instanceof Collection<?>) {
                     newValues.addAll((Collection<?>) obj);
                 } else {
                     newValues.add(obj);
                 }
             }
             Object array = Array.newInstance(type, newValues.size());
             field.set(command, array);
             for (int i = 0; i < newValues.size(); i++) {
                 Array.set(array, i, newValues.get(i));
             }
             return converted.size(); // return how many args were consumed
         }
 
         @SuppressWarnings("unchecked")
         private int applyValuesToCollectionField(Field field,
                                                  Class<?> annotation,
                                                  Range arity,
                                                  Stack<String> args,
                                                  Class<?> cls,
                                                  String argDescription) throws Exception {
             Collection<Object> collection = (Collection<Object>) field.get(command);
             Class<?> type = getTypeAttribute(field)[0];
             int length = collection == null ? 0 : collection.size();
             List<Object> converted = consumeArguments(field, annotation, arity, args, type, length, argDescription);
             if (collection == null) {
                 collection = createCollection(cls);
                 field.set(command, collection);
             }
             for (Object element : converted) {
                 if (element instanceof Collection<?>) {
                     collection.addAll((Collection<?>) element);
                 } else {
                     collection.add(element);
                 }
             }
             return converted.size();
         }
 
         private List<Object> consumeArguments(Field field,
                                               Class<?> annotation,
                                               Range arity,
                                               Stack<String> args,
                                               Class<?> type,
                                               int originalSize,
                                               String argDescription) throws Exception {
             List<Object> result = new ArrayList<Object>();
 
             // first do the arity.min mandatory parameters
             for (int i = 0; i < arity.min; i++) {
                 consumeOneArgument(field, arity, args, type, result, i, originalSize, argDescription);
             }
             // now process the varargs if any
             for (int i = arity.min; i < arity.max && !args.isEmpty(); i++) {
                 if (annotation != Parameters.class) { // for vararg Options, we stop if we encounter '--', a command, or another option
                     if (commands.containsKey(args.peek()) || isOption(args.peek())) {
                         return result;
                     }
                 }
                 consumeOneArgument(field, arity, args, type, result, i, originalSize, argDescription);
             }
             return result;
         }
 
         private int consumeOneArgument(Field field,
                                        Range arity,
                                        Stack<String> args,
                                        Class<?> type,
                                        List<Object> result,
                                        int index,
                                        int originalSize,
                                        String argDescription) throws Exception {
             String[] values = split(trim(args.pop()), field);
             ITypeConverter<?> converter = getTypeConverter(type, field);
 
             for (int j = 0; j < values.length; j++) {
                 result.add(tryConvert(field, index, converter, values[j], type));
                 if (tracer.isInfo()) {
                     if (field.getType().isArray()) {
                         tracer.info("Adding [%s] to %s[] field '%s.%s' for %s%n", String.valueOf(result.get(result.size() - 1)), type.getSimpleName(), field.getDeclaringClass().getSimpleName(), field.getName(), argDescription);
                     } else {
                         tracer.info("Adding [%s] to %s<%s> field '%s.%s' for %s%n", String.valueOf(result.get(result.size() - 1)), field.getType().getSimpleName(), type.getSimpleName(), field.getDeclaringClass().getSimpleName(), field.getName(), argDescription);
                     }
                 }
             }
             //checkMaxArityExceeded(arity, max, field, values);
             return ++index;
         }
 
         private String splitRegex(Field field) {
             if (field.isAnnotationPresent(Option.class))     { return field.getAnnotation(Option.class).split(); }
             if (field.isAnnotationPresent(Parameters.class)) { return field.getAnnotation(Parameters.class).split(); }
             return "";
         }
         private String[] split(String value, Field field) {
             String regex = splitRegex(field);
             return regex.length() == 0 ? new String[] {value} : value.split(regex);
         }
 
         /**
          * Called when parsing varargs parameters for a multi-value option.
          * When an option is encountered, the remainder should not be interpreted as vararg elements.
          * @param arg the string to determine whether it is an option or not
          * @return true if it is an option, false otherwise
          */
         private boolean isOption(String arg) {
             if ("--".equals(arg)) {
                 return true;
             }
             // not just arg prefix: we may be in the middle of parsing -xrvfFILE
             if (optionName2Field.containsKey(arg)) { // -v or -f or --file (not attached to param or other option)
                 return true;
             }
             int separatorIndex = arg.indexOf(separator);
             if (separatorIndex > 0) { // -f=FILE or --file==FILE (attached to param via separator)
                 if (optionName2Field.containsKey(arg.substring(0, separatorIndex))) {
                     return true;
                 }
             }
             return (arg.length() > 2 && arg.startsWith("-") && singleCharOption2Field.containsKey(arg.charAt(1)));
         }
         private Object tryConvert(Field field, int index, ITypeConverter<?> converter, String value, Class<?> type)
                 throws Exception {
             try {
                 return converter.convert(value);
             } catch (TypeConversionException ex) {
                 throw new ParameterException(CommandLine.this, ex.getMessage() + optionDescription(" for ", field, index));
             } catch (Exception other) {
                 String desc = optionDescription(" for ", field, index) + ": " + other;
                 throw new ParameterException(CommandLine.this, "Could not convert '" + value + "' to " + type.getSimpleName() + desc, other);
             }
         }
 
         private String optionDescription(String prefix, Field field, int index) {
             Help.IParamLabelRenderer labelRenderer = Help.createMinimalParamLabelRenderer();
             String desc = "";
             if (field.isAnnotationPresent(Option.class)) {
                 desc = prefix + "option '" + field.getAnnotation(Option.class).names()[0] + "'";
                 if (index >= 0) {
                     Range arity = Range.optionArity(field);
                     if (arity.max > 1) {
                         desc += " at index " + index;
                     }
                     desc += " (" + labelRenderer.renderParameterLabel(field, Help.Ansi.OFF, Collections.<IStyle>emptyList()) + ")";
                 }
             } else if (field.isAnnotationPresent(Parameters.class)) {
                 Range indexRange = Range.parameterIndex(field);
                 Text label = labelRenderer.renderParameterLabel(field, Help.Ansi.OFF, Collections.<IStyle>emptyList());
                 desc = prefix + "positional parameter at index " + indexRange + " (" + label + ")";
             }
             return desc;
         }
 
         private boolean isAnyHelpRequested() { return isHelpRequested || versionHelpRequested || usageHelpRequested; }
 
         private void updateHelpRequested(Field field) {
             if (field.isAnnotationPresent(Option.class)) {
                 isHelpRequested                       |= is(field, "help", field.getAnnotation(Option.class).help());
                 CommandLine.this.versionHelpRequested |= is(field, "versionHelp", field.getAnnotation(Option.class).versionHelp());
                 CommandLine.this.usageHelpRequested   |= is(field, "usageHelp", field.getAnnotation(Option.class).usageHelp());
             }
         }
         private boolean is(Field f, String description, boolean value) {
             if (value) { if (tracer.isInfo()) {tracer.info("Field '%s.%s' has '%s' annotation: not validating required fields%n", f.getDeclaringClass().getSimpleName(), f.getName(), description); }}
             return value;
         }
         @SuppressWarnings("unchecked")
         private Collection<Object> createCollection(Class<?> collectionClass) throws Exception {
             if (collectionClass.isInterface()) {
                 if (List.class.isAssignableFrom(collectionClass)) {
                     return new ArrayList<Object>();
                 } else if (SortedSet.class.isAssignableFrom(collectionClass)) {
                     return new TreeSet<Object>();
                 } else if (Set.class.isAssignableFrom(collectionClass)) {
                     return new LinkedHashSet<Object>();
                 } else if (Queue.class.isAssignableFrom(collectionClass)) {
                     return new LinkedList<Object>(); // ArrayDeque is only available since 1.6
                 }
                 return new ArrayList<Object>();
             }
             // custom Collection implementation class must have default constructor
             return (Collection<Object>) collectionClass.newInstance();
         }
         private Map<Object, Object> createMap(Class<?> mapClass) throws Exception {
             try { // if it is an implementation class, instantiate it
                 return (Map<Object, Object>) mapClass.newInstance();
             } catch (Exception ignored) {}
             return new LinkedHashMap<Object, Object>();
         }
         private ITypeConverter<?> getTypeConverter(final Class<?> type, Field field) {
             ITypeConverter<?> result = converterRegistry.get(type);
             if (result != null) {
                 return result;
             }
             if (type.isEnum()) {
                 return new ITypeConverter<Object>() {
                     @SuppressWarnings("unchecked")
                     public Object convert(String value) throws Exception {
                         return Enum.valueOf((Class<Enum>) type, value);
                     }
                 };
             }
             throw new MissingTypeConverterException(CommandLine.this, "No TypeConverter registered for " + type.getName() + " of field " + field);
         }
 
         private void assertNoMissingParameters(Field field, int arity, Stack<String> args) {
             if (arity > args.size()) {
                 if (arity == 1) {
                     if (field.isAnnotationPresent(Option.class)) {
                         throw new MissingParameterException(CommandLine.this, "Missing required parameter for " +
                                 optionDescription("", field, 0));
                     }
                     Range indexRange = Range.parameterIndex(field);
                     Help.IParamLabelRenderer labelRenderer = Help.createMinimalParamLabelRenderer();
                     String sep = "";
                     String names = "";
                     int count = 0;
                     for (int i = indexRange.min; i < positionalParametersFields.size(); i++) {
                         if (Range.parameterArity(positionalParametersFields.get(i)).min > 0) {
                             names += sep + labelRenderer.renderParameterLabel(positionalParametersFields.get(i),
                                     Help.Ansi.OFF, Collections.<IStyle>emptyList());
                             sep = ", ";
                             count++;
                         }
                     }
                     String msg = "Missing required parameter";
                     Range paramArity = Range.parameterArity(field);
                     if (paramArity.isVariable) {
                         msg += "s at positions " + indexRange + ": ";
                     } else {
                         msg += (count > 1 ? "s: " : ": ");
                     }
                     throw new MissingParameterException(CommandLine.this, msg + names);
                 }
                 if (args.isEmpty()) {
                     throw new MissingParameterException(CommandLine.this, optionDescription("", field, 0) +
                             " requires at least " + arity + " values, but none were specified.");
                 }
                 throw new MissingParameterException(CommandLine.this, optionDescription("", field, 0) +
                         " requires at least " + arity + " values, but only " + args.size() + " were specified: " + reverse(args));
             }
         }
         private String trim(String value) {
             return unquote(value);
         }
 
         private String unquote(String value) {
             return value == null
                     ? null
                     : (value.length() > 1 && value.startsWith("\"") && value.endsWith("\""))
                         ? value.substring(1, value.length() - 1)
                         : value;
         }
     }
     private static class PositionalParametersSorter implements Comparator<Field> {
         public int compare(Field o1, Field o2) {
             int result = Range.parameterIndex(o1).compareTo(Range.parameterIndex(o2));
             return (result == 0) ? Range.parameterArity(o1).compareTo(Range.parameterArity(o2)) : result;
         }
     }
     /**
      * Inner class to group the built-in {@link ITypeConverter} implementations.
      */
     private static class BuiltIn {
         static class PathConverter implements ITypeConverter<Path> {
             @Override public Path convert(final String value) { return Paths.get(value); }
         }
         static class StringConverter implements ITypeConverter<String> {
             public String convert(String value) { return value; }
         }
         static class StringBuilderConverter implements ITypeConverter<StringBuilder> {
             public StringBuilder convert(String value) { return new StringBuilder(value); }
         }
         static class CharSequenceConverter implements ITypeConverter<CharSequence> {
             public String convert(String value) { return value; }
         }
         /** Converts text to a {@code Byte} by delegating to {@link Byte#valueOf(String)}.*/
         static class ByteConverter implements ITypeConverter<Byte> {
             public Byte convert(String value) { return Byte.valueOf(value); }
         }
         /** Converts {@code "true"} or {@code "false"} to a {@code Boolean}. Other values result in a ParameterException.*/
         static class BooleanConverter implements ITypeConverter<Boolean> {
             public Boolean convert(String value) {
                 if ("true".equalsIgnoreCase(value) || "false".equalsIgnoreCase(value)) {
                     return Boolean.parseBoolean(value);
                 } else {
                     throw new TypeConversionException("'" + value + "' is not a boolean");
                 }
             }
         }
         static class CharacterConverter implements ITypeConverter<Character> {
             public Character convert(String value) {
                 if (value.length() > 1) {
                     throw new TypeConversionException("'" + value + "' is not a single character");
                 }
                 return value.charAt(0);
             }
         }
         /** Converts text to a {@code Short} by delegating to {@link Short#valueOf(String)}.*/
         static class ShortConverter implements ITypeConverter<Short> {
             public Short convert(String value) { return Short.valueOf(value); }
         }
         /** Converts text to an {@code Integer} by delegating to {@link Integer#valueOf(String)}.*/
         static class IntegerConverter implements ITypeConverter<Integer> {
             public Integer convert(String value) { return Integer.valueOf(value); }
         }
         /** Converts text to a {@code Long} by delegating to {@link Long#valueOf(String)}.*/
         static class LongConverter implements ITypeConverter<Long> {
             public Long convert(String value) { return Long.valueOf(value); }
         }
         static class FloatConverter implements ITypeConverter<Float> {
             public Float convert(String value) { return Float.valueOf(value); }
         }
         static class DoubleConverter implements ITypeConverter<Double> {
             public Double convert(String value) { return Double.valueOf(value); }
         }
         static class FileConverter implements ITypeConverter<File> {
             public File convert(String value) { return new File(value); }
         }
         static class URLConverter implements ITypeConverter<URL> {
             public URL convert(String value) throws MalformedURLException { return new URL(value); }
         }
         static class URIConverter implements ITypeConverter<URI> {
             public URI convert(String value) throws URISyntaxException { return new URI(value); }
         }
         /** Converts text in {@code yyyy-mm-dd} format to a {@code java.util.Date}. ParameterException on failure. */
         static class ISO8601DateConverter implements ITypeConverter<Date> {
             public Date convert(String value) {
                 try {
                     return new SimpleDateFormat("yyyy-MM-dd").parse(value);
                 } catch (ParseException e) {
                     throw new TypeConversionException("'" + value + "' is not a yyyy-MM-dd date");
                 }
             }
         }
         /** Converts text in any of the following formats to a {@code java.sql.Time}: {@code HH:mm}, {@code HH:mm:ss},
          * {@code HH:mm:ss.SSS}, {@code HH:mm:ss,SSS}. Other formats result in a ParameterException. */
         static class ISO8601TimeConverter implements ITypeConverter<Time> {
             public Time convert(String value) {
                 try {
                     if (value.length() <= 5) {
                         return new Time(new SimpleDateFormat("HH:mm").parse(value).getTime());
                     } else if (value.length() <= 8) {
                         return new Time(new SimpleDateFormat("HH:mm:ss").parse(value).getTime());
                     } else if (value.length() <= 12) {
                         try {
                             return new Time(new SimpleDateFormat("HH:mm:ss.SSS").parse(value).getTime());
                         } catch (ParseException e2) {
                             return new Time(new SimpleDateFormat("HH:mm:ss,SSS").parse(value).getTime());
                         }
                     }
                 } catch (ParseException ignored) {
                     // ignored because we throw a ParameterException below
                 }
                 throw new TypeConversionException("'" + value + "' is not a HH:mm[:ss[.SSS]] time");
             }
         }
         static class BigDecimalConverter implements ITypeConverter<BigDecimal> {
             public BigDecimal convert(String value) { return new BigDecimal(value); }
         }
         static class BigIntegerConverter implements ITypeConverter<BigInteger> {
             public BigInteger convert(String value) { return new BigInteger(value); }
         }
         static class CharsetConverter implements ITypeConverter<Charset> {
             public Charset convert(String s) { return Charset.forName(s); }
         }
         /** Converts text to a {@code InetAddress} by delegating to {@link InetAddress#getByName(String)}. */
         static class InetAddressConverter implements ITypeConverter<InetAddress> {
             public InetAddress convert(String s) throws Exception { return InetAddress.getByName(s); }
         }
         static class PatternConverter implements ITypeConverter<Pattern> {
             public Pattern convert(String s) { return Pattern.compile(s); }
         }
         static class UUIDConverter implements ITypeConverter<UUID> {
             public UUID convert(String s) throws Exception { return UUID.fromString(s); }
         }
         private BuiltIn() {} // private constructor: never instantiate
     }
 
     /**
      * A collection of methods and inner classes that provide fine-grained control over the contents and layout of
      * the usage help message to display to end users when help is requested or invalid input values were specified.
      * <h3>Layered API</h3>
      * <p>The {@link Command} annotation provides the easiest way to customize usage help messages. See
      * the <a href="https://remkop.github.io/picocli/index.html#_usage_help">Manual</a> for details.</p>
      * <p>This Help class provides high-level functions to create sections of the usage help message and headings
      * for these sections. Instead of calling the {@link CommandLine#usage(PrintStream, CommandLine.Help.ColorScheme)}
      * method, application authors may want to create a custom usage help message by reorganizing sections in a
      * different order and/or adding custom sections.</p>
      * <p>Finally, the Help class contains inner classes and interfaces that can be used to create custom help messages.</p>
      * <h4>IOptionRenderer and IParameterRenderer</h4>
      * <p>Renders a field annotated with {@link Option} or {@link Parameters} to an array of {@link Text} values.
      * By default, these values are</p><ul>
      * <li>mandatory marker character (if the option/parameter is {@link Option#required() required})</li>
      * <li>short option name (empty for parameters)</li>
      * <li>comma or empty (empty for parameters)</li>
      * <li>long option names (the parameter {@link IParamLabelRenderer label} for parameters)</li>
      * <li>description</li>
      * </ul>
      * <p>Other components rely on this ordering.</p>
      * <h4>Layout</h4>
      * <p>Delegates to the renderers to create {@link Text} values for the annotated fields, and uses a
      * {@link TextTable} to display these values in tabular format. Layout is responsible for deciding which values
      * to display where in the table. By default, Layout shows one option or parameter per table row.</p>
      * <h4>TextTable</h4>
      * <p>Responsible for spacing out {@link Text} values according to the {@link Column} definitions the table was
      * created with. Columns have a width, indentation, and an overflow policy that decides what to do if a value is
      * longer than the column's width.</p>
      * <h4>Text</h4>
      * <p>Encapsulates rich text with styles and colors in a way that other components like {@link TextTable} are
      * unaware of the embedded ANSI escape codes.</p>
      */
     public static class Help {
         /** Constant String holding the default program name: {@value} */
         protected static final String DEFAULT_COMMAND_NAME = "<main class>";
 
         /** Constant String holding the default string that separates options from option parameters: {@value} */
         protected static final String DEFAULT_SEPARATOR = "=";
 
         private final static int usageHelpWidth = 80;
         private final static int optionsColumnWidth = 2 + 2 + 1 + 24;
         private final Object command;
         private final Map<String, Help> commands = new LinkedHashMap<String, Help>();
         final ColorScheme colorScheme;
 
         /** Immutable list of fields annotated with {@link Option}, in declaration order. */
         public final List<Field> optionFields;
 
         /** Immutable list of fields annotated with {@link Parameters}, or an empty list if no such field exists. */
         public final List<Field> positionalParametersFields;
 
         /** The String to use as the separator between options and option parameters. {@code "="} by default,
          * initialized from {@link Command#separator()} if defined.
          * @see #parameterLabelRenderer */
         public String separator;
 
         /** The String to use as the program name in the synopsis line of the help message.
          * {@link #DEFAULT_COMMAND_NAME} by default, initialized from {@link Command#name()} if defined. */
         public String commandName = DEFAULT_COMMAND_NAME;
 
         /** Optional text lines to use as the description of the help message, displayed between the synopsis and the
          * options list. Initialized from {@link Command#description()} if the {@code Command} annotation is present,
          * otherwise this is an empty array and the help message has no description.
          * Applications may programmatically set this field to create a custom help message. */
         public String[] description = {};
 
         /** Optional custom synopsis lines to use instead of the auto-generated synopsis.
          * Initialized from {@link Command#customSynopsis()} if the {@code Command} annotation is present,
          * otherwise this is an empty array and the synopsis is generated.
          * Applications may programmatically set this field to create a custom help message. */
         public String[] customSynopsis = {};
 
         /** Optional header lines displayed at the top of the help message. For subcommands, the first header line is
          * displayed in the list of commands. Values are initialized from {@link Command#header()}
          * if the {@code Command} annotation is present, otherwise this is an empty array and the help message has no
          * header. Applications may programmatically set this field to create a custom help message. */
         public String[] header = {};
 
         /** Optional footer text lines displayed at the bottom of the help message. Initialized from
          * {@link Command#footer()} if the {@code Command} annotation is present, otherwise this is an empty array and
          * the help message has no footer.
          * Applications may programmatically set this field to create a custom help message. */
         public String[] footer = {};
 
         /** Option and positional parameter value label renderer used for the synopsis line(s) and the option list.
          * By default initialized to the result of {@link #createDefaultParamLabelRenderer()}, which takes a snapshot
          * of the {@link #separator} at construction time. If the separator is modified after Help construction, you
          * may need to re-initialize this field by calling {@link #createDefaultParamLabelRenderer()} again. */
         public IParamLabelRenderer parameterLabelRenderer;
 
         /** If {@code true}, the synopsis line(s) will show an abbreviated synopsis without detailed option names. */
         public Boolean abbreviateSynopsis;
 
         /** If {@code true}, the options list is sorted alphabetically. */
         public Boolean sortOptions;
 
         /** If {@code true}, the options list will show default values for all options except booleans. */
         public Boolean showDefaultValues;
 
         /** Character used to prefix required options in the options list. */
         public Character requiredOptionMarker;
 
         /** Optional heading preceding the header section. Initialized from {@link Command#headerHeading()}, or null. */
         public String headerHeading;
 
         /** Optional heading preceding the synopsis. Initialized from {@link Command#synopsisHeading()}, {@code "Usage: "} by default. */
         public String synopsisHeading;
 
         /** Optional heading preceding the description section. Initialized from {@link Command#descriptionHeading()}, or null. */
         public String descriptionHeading;
 
         /** Optional heading preceding the parameter list. Initialized from {@link Command#parameterListHeading()}, or null. */
         public String parameterListHeading;
 
         /** Optional heading preceding the options list. Initialized from {@link Command#optionListHeading()}, or null. */
         public String optionListHeading;
 
         /** Optional heading preceding the subcommand list. Initialized from {@link Command#commandListHeading()}. {@code "Commands:%n"} by default. */
         public String commandListHeading;
 
         /** Optional heading preceding the footer section. Initialized from {@link Command#footerHeading()}, or null. */
         public String footerHeading;
 
         /** Constructs a new {@code Help} instance with a default color scheme, initialized from annotatations
          * on the specified class and superclasses.
          * @param command the annotated object to create usage help for */
         public Help(Object command) {
             this(command, Ansi.AUTO);
         }
 
         /** Constructs a new {@code Help} instance with a default color scheme, initialized from annotatations
          * on the specified class and superclasses.
          * @param command the annotated object to create usage help for
          * @param ansi whether to emit ANSI escape codes or not */
         public Help(Object command, Ansi ansi) {
             this(command, defaultColorScheme(ansi));
         }
 
         /** Constructs a new {@code Help} instance with the specified color scheme, initialized from annotatations
          * on the specified class and superclasses.
          * @param command the annotated object to create usage help for
          * @param colorScheme the color scheme to use */
         public Help(Object command, ColorScheme colorScheme) {
             this.command = Assert.notNull(command, "command");
             this.colorScheme = Assert.notNull(colorScheme, "colorScheme").applySystemProperties();
             List<Field> options = new ArrayList<Field>();
             List<Field> operands = new ArrayList<Field>();
             Class<?> cls = command.getClass();
             while (cls != null) {
                 for (Field field : cls.getDeclaredFields()) {
                     field.setAccessible(true);
                     if (field.isAnnotationPresent(Option.class)) {
                         Option option = field.getAnnotation(Option.class);
                         if (!option.hidden()) { // hidden options should not appear in usage help
                             // TODO remember longest concatenated option string length (issue #45)
                             options.add(field);
                         }
                     }
                     if (field.isAnnotationPresent(Parameters.class)) {
                         operands.add(field);
                     }
                 }
                 // superclass values should not overwrite values if both class and superclass have a @Command annotation
                 if (cls.isAnnotationPresent(Command.class)) {
                     Command cmd = cls.getAnnotation(Command.class);
                     if (DEFAULT_COMMAND_NAME.equals(commandName)) {
                         commandName = cmd.name();
                     }
                     separator = (separator == null) ? cmd.separator() : separator;
                     abbreviateSynopsis = (abbreviateSynopsis == null) ? cmd.abbreviateSynopsis() : abbreviateSynopsis;
                     sortOptions = (sortOptions == null) ? cmd.sortOptions() : sortOptions;
                     requiredOptionMarker = (requiredOptionMarker == null) ? cmd.requiredOptionMarker() : requiredOptionMarker;
                     showDefaultValues = (showDefaultValues == null) ? cmd.showDefaultValues() : showDefaultValues;
                     customSynopsis = empty(customSynopsis) ? cmd.customSynopsis() : customSynopsis;
                     description = empty(description) ? cmd.description() : description;
                     header = empty(header) ? cmd.header() : header;
                     footer = empty(footer) ? cmd.footer() : footer;
                     headerHeading = empty(headerHeading) ? cmd.headerHeading() : headerHeading;
                     synopsisHeading = empty(synopsisHeading) || "Usage: ".equals(synopsisHeading) ? cmd.synopsisHeading() : synopsisHeading;
                     descriptionHeading = empty(descriptionHeading) ? cmd.descriptionHeading() : descriptionHeading;
                     parameterListHeading = empty(parameterListHeading) ? cmd.parameterListHeading() : parameterListHeading;
                     optionListHeading = empty(optionListHeading) ? cmd.optionListHeading() : optionListHeading;
                     commandListHeading = empty(commandListHeading) || "Commands:%n".equals(commandListHeading) ? cmd.commandListHeading() : commandListHeading;
                     footerHeading = empty(footerHeading) ? cmd.footerHeading() : footerHeading;
                 }
                 cls = cls.getSuperclass();
             }
             sortOptions =          (sortOptions == null)          ? true : sortOptions;
             abbreviateSynopsis =   (abbreviateSynopsis == null)   ? false : abbreviateSynopsis;
             requiredOptionMarker = (requiredOptionMarker == null) ? ' ' : requiredOptionMarker;
             showDefaultValues =    (showDefaultValues == null)    ? false : showDefaultValues;
             synopsisHeading =      (synopsisHeading == null)      ? "Usage: " : synopsisHeading;
             commandListHeading =   (commandListHeading == null)   ? "Commands:%n" : commandListHeading;
             separator =            (separator == null)            ? DEFAULT_SEPARATOR : separator;
             parameterLabelRenderer = createDefaultParamLabelRenderer(); // uses help separator
             Collections.sort(operands, new PositionalParametersSorter());
             positionalParametersFields = Collections.unmodifiableList(operands);
             optionFields                 = Collections.unmodifiableList(options);
         }
 
         /** Registers all specified subcommands with this Help.
          * @param commands maps the command names to the associated CommandLine object
          * @return this Help instance (for method chaining)
          * @see CommandLine#getSubcommands()
          */
         public Help addAllSubcommands(Map<String, CommandLine> commands) {
             if (commands != null) {
                 for (Map.Entry<String, CommandLine> entry : commands.entrySet()) {
                     addSubcommand(entry.getKey(), entry.getValue().getCommand());
                 }
             }
             return this;
         }
 
         /** Registers the specified subcommand with this Help.
          * @param commandName the name of the subcommand to display in the usage message
          * @param command the annotated object to get more information from
          * @return this Help instance (for method chaining)
          */
         public Help addSubcommand(String commandName, Object command) {
             commands.put(commandName, new Help(command));
             return this;
         }
 
         /** Returns a synopsis for the command without reserving space for the synopsis heading.
          * @return a synopsis
          * @see #abbreviatedSynopsis()
          * @see #detailedSynopsis(Comparator, boolean)
          * @deprecated use {@link #synopsis(int)} instead
          */
         public String synopsis() { return synopsis(0); }
 
         /**
          * Returns a synopsis for the command, reserving the specified space for the synopsis heading.
          * @param synopsisHeadingLength the length of the synopsis heading that will be displayed on the same line
          * @return a synopsis
          * @see #abbreviatedSynopsis()
          * @see #detailedSynopsis(Comparator, boolean)
          * @see #synopsisHeading
          */
         public String synopsis(int synopsisHeadingLength) {
             if (!empty(customSynopsis)) { return customSynopsis(); }
             return abbreviateSynopsis ? abbreviatedSynopsis()
                     : detailedSynopsis(synopsisHeadingLength, createShortOptionArityAndNameComparator(), true);
         }
 
         /** Generates a generic synopsis like {@code <command name> [OPTIONS] [PARAM1 [PARAM2]...]}, omitting parts
          * that don't apply to the command (e.g., does not show [OPTIONS] if the command has no options).
          * @return a generic synopsis */
         public String abbreviatedSynopsis() {
             StringBuilder sb = new StringBuilder();
             if (!optionFields.isEmpty()) { // only show if annotated object actually has options
                 sb.append(" [OPTIONS]");
             }
             // sb.append(" [--] "); // implied
             for (Field positionalParam : positionalParametersFields) {
                 if (!positionalParam.getAnnotation(Parameters.class).hidden()) {
                     sb.append(' ').append(parameterLabelRenderer.renderParameterLabel(positionalParam, ansi(), colorScheme.parameterStyles));
                 }
             }
             return colorScheme.commandText(commandName).toString()
                     + (sb.toString()) + System.getProperty("line.separator");
         }
         /** Generates a detailed synopsis message showing all options and parameters. Follows the unix convention of
          * showing optional options and parameters in square brackets ({@code [ ]}).
          * @param optionSort comparator to sort options or {@code null} if options should not be sorted
          * @param clusterBooleanOptions {@code true} if boolean short options should be clustered into a single string
          * @return a detailed synopsis
          * @deprecated use {@link #detailedSynopsis(int, Comparator, boolean)} instead. */
         public String detailedSynopsis(Comparator<Field> optionSort, boolean clusterBooleanOptions) {
             return detailedSynopsis(0, optionSort, clusterBooleanOptions);
         }
 
         /** Generates a detailed synopsis message showing all options and parameters. Follows the unix convention of
          * showing optional options and parameters in square brackets ({@code [ ]}).
          * @param synopsisHeadingLength the length of the synopsis heading that will be displayed on the same line
          * @param optionSort comparator to sort options or {@code null} if options should not be sorted
          * @param clusterBooleanOptions {@code true} if boolean short options should be clustered into a single string
          * @return a detailed synopsis */
         public String detailedSynopsis(int synopsisHeadingLength, Comparator<Field> optionSort, boolean clusterBooleanOptions) {
             Text optionText = ansi().new Text(0);
             List<Field> fields = new ArrayList<Field>(optionFields); // iterate in declaration order
             if (optionSort != null) {
                 Collections.sort(fields, optionSort);// iterate in specified sort order
             }
             if (clusterBooleanOptions) { // cluster all short boolean options into a single string
                 List<Field> booleanOptions = new ArrayList<Field>();
                 StringBuilder clusteredRequired = new StringBuilder("-");
                 StringBuilder clusteredOptional = new StringBuilder("-");
                 for (Field field : fields) {
                     if (field.getType() == boolean.class || field.getType() == Boolean.class) {
                         Option option = field.getAnnotation(Option.class);
                         String shortestName = ShortestFirst.sort(option.names())[0];
                         if (shortestName.length() == 2 && shortestName.startsWith("-")) {
                             booleanOptions.add(field);
                             if (option.required()) {
                                 clusteredRequired.append(shortestName.substring(1));
                             } else {
                                 clusteredOptional.append(shortestName.substring(1));
                             }
                         }
                     }
                 }
                 fields.removeAll(booleanOptions);
                 if (clusteredRequired.length() > 1) { // initial length was 1
                     optionText = optionText.append(" ").append(colorScheme.optionText(clusteredRequired.toString()));
                 }
                 if (clusteredOptional.length() > 1) { // initial length was 1
                     optionText = optionText.append(" [").append(colorScheme.optionText(clusteredOptional.toString())).append("]");
                 }
             }
             for (Field field : fields) {
                 Option option = field.getAnnotation(Option.class);
                 if (!option.hidden()) {
                     if (option.required()) {
                         optionText = appendOptionSynopsis(optionText, field, ShortestFirst.sort(option.names())[0], " ", "");
                         if (isMultiValue(field)) {
                             optionText = appendOptionSynopsis(optionText, field, ShortestFirst.sort(option.names())[0], " [", "]...");
                         }
                     } else {
                         optionText = appendOptionSynopsis(optionText, field, ShortestFirst.sort(option.names())[0], " [", "]");
                         if (isMultiValue(field)) {
                             optionText = optionText.append("...");
                         }
                     }
                 }
             }
             for (Field positionalParam : positionalParametersFields) {
                 if (!positionalParam.getAnnotation(Parameters.class).hidden()) {
                     optionText = optionText.append(" ");
                     Text label = parameterLabelRenderer.renderParameterLabel(positionalParam, colorScheme.ansi(), colorScheme.parameterStyles);
                     optionText = optionText.append(label);
                 }
             }
             // Fix for #142: first line of synopsis overshoots max. characters
             int firstColumnLength = commandName.length() + synopsisHeadingLength;
 
             // synopsis heading ("Usage: ") may be on the same line, so adjust column width
             TextTable textTable = new TextTable(ansi(), firstColumnLength, usageHelpWidth - firstColumnLength);
             textTable.indentWrappedLines = 1; // don't worry about first line: options (2nd column) always start with a space
 
             // right-adjust the command name by length of synopsis heading
             Text PADDING = Ansi.OFF.new Text(stringOf('X', synopsisHeadingLength));
             textTable.addRowValues(new Text[] {PADDING.append(colorScheme.commandText(commandName)), optionText});
             return textTable.toString().substring(synopsisHeadingLength); // cut off leading synopsis heading spaces
         }
 
         private Text appendOptionSynopsis(Text optionText, Field field, String optionName, String prefix, String suffix) {
             Text optionParamText = parameterLabelRenderer.renderParameterLabel(field, colorScheme.ansi(), colorScheme.optionParamStyles);
             return optionText.append(prefix)
                     .append(colorScheme.optionText(optionName))
                     .append(optionParamText)
                     .append(suffix);
         }
 
         /** Returns the number of characters the synopsis heading will take on the same line as the synopsis.
          * @return the number of characters the synopsis heading will take on the same line as the synopsis.
          * @see #detailedSynopsis(int, Comparator, boolean)
          */
         public int synopsisHeadingLength() {
             String[] lines = Ansi.OFF.new Text(synopsisHeading).toString().split("\\r?\\n|\\r|%n", -1);
             return lines[lines.length - 1].length();
         }
         /**
          * <p>Returns a description of the {@linkplain Option options} supported by the application.
          * This implementation {@linkplain #createShortOptionNameComparator() sorts options alphabetically}, and shows
          * only the {@linkplain Option#hidden() non-hidden} options in a {@linkplain TextTable tabular format}
          * using the {@linkplain #createDefaultOptionRenderer() default renderer} and {@linkplain Layout default layout}.</p>
          * @return the fully formatted option list
          * @see #optionList(Layout, Comparator, IParamLabelRenderer)
          */
         public String optionList() {
             Comparator<Field> sortOrder = sortOptions == null || sortOptions.booleanValue()
                     ? createShortOptionNameComparator()
                     : null;
             return optionList(createDefaultLayout(), sortOrder, parameterLabelRenderer);
         }
 
         /** Sorts all {@code Options} with the specified {@code comparator} (if the comparator is non-{@code null}),
          * then {@linkplain Layout#addOption(Field, CommandLine.Help.IParamLabelRenderer) adds} all non-hidden options to the
          * specified TextTable and returns the result of TextTable.toString().
          * @param layout responsible for rendering the option list
          * @param optionSort determines in what order {@code Options} should be listed. Declared order if {@code null}
          * @param valueLabelRenderer used for options with a parameter
          * @return the fully formatted option list
          */
         public String optionList(Layout layout, Comparator<Field> optionSort, IParamLabelRenderer valueLabelRenderer) {
             List<Field> fields = new ArrayList<Field>(optionFields); // options are stored in order of declaration
             if (optionSort != null) {
                 Collections.sort(fields, optionSort); // default: sort options ABC
             }
             layout.addOptions(fields, valueLabelRenderer);
             return layout.toString();
         }
 
         /**
          * Returns the section of the usage help message that lists the parameters with their descriptions.
          * @return the section of the usage help message that lists the parameters
          */
         public String parameterList() {
             return parameterList(createDefaultLayout(), parameterLabelRenderer);
         }
         /**
          * Returns the section of the usage help message that lists the parameters with their descriptions.
          * @param layout the layout to use
          * @param paramLabelRenderer for rendering parameter names
          * @return the section of the usage help message that lists the parameters
          */
         public String parameterList(Layout layout, IParamLabelRenderer paramLabelRenderer) {
             layout.addPositionalParameters(positionalParametersFields, paramLabelRenderer);
             return layout.toString();
         }
 
         private static String heading(Ansi ansi, String values, Object... params) {
             StringBuilder sb = join(ansi, new String[] {values}, new StringBuilder(), params);
             String result = sb.toString();
             result = result.endsWith(System.getProperty("line.separator"))
                     ? result.substring(0, result.length() - System.getProperty("line.separator").length()) : result;
             return result + new String(spaces(countTrailingSpaces(values)));
         }
         private static char[] spaces(int length) { char[] result = new char[length]; Arrays.fill(result, ' '); return result; }
         private static int countTrailingSpaces(String str) {
             if (str == null) {return 0;}
             int trailingSpaces = 0;
             for (int i = str.length() - 1; i >= 0 && str.charAt(i) == ' '; i--) { trailingSpaces++; }
             return trailingSpaces;
         }
 
         /** Formats each of the specified values and appends it to the specified StringBuilder.
          * @param ansi whether the result should contain ANSI escape codes or not
          * @param values the values to format and append to the StringBuilder
          * @param sb the StringBuilder to collect the formatted strings
          * @param params the parameters to pass to the format method when formatting each value
          * @return the specified StringBuilder */
         public static StringBuilder join(Ansi ansi, String[] values, StringBuilder sb, Object... params) {
             if (values != null) {
                 TextTable table = new TextTable(ansi, usageHelpWidth);
                 table.indentWrappedLines = 0;
                 for (String summaryLine : values) {
                     Text[] lines = ansi.new Text(format(summaryLine, params)).splitLines();
                     for (Text line : lines) {  table.addRowValues(line); }
                 }
                 table.toString(sb);
             }
             return sb;
         }
         private static String format(String formatString,  Object... params) {
             return formatString == null ? "" : String.format(formatString, params);
         }
         /** Returns command custom synopsis as a string. A custom synopsis can be zero or more lines, and can be
          * specified declaratively with the {@link Command#customSynopsis()} annotation attribute or programmatically
          * by setting the Help instance's {@link Help#customSynopsis} field.
          * @param params Arguments referenced by the format specifiers in the synopsis strings
          * @return the custom synopsis lines combined into a single String (which may be empty)
          */
         public String customSynopsis(Object... params) {
             return join(ansi(), customSynopsis, new StringBuilder(), params).toString();
         }
         /** Returns command description text as a string. Description text can be zero or more lines, and can be specified
          * declaratively with the {@link Command#description()} annotation attribute or programmatically by
          * setting the Help instance's {@link Help#description} field.
          * @param params Arguments referenced by the format specifiers in the description strings
          * @return the description lines combined into a single String (which may be empty)
          */
         public String description(Object... params) {
             return join(ansi(), description, new StringBuilder(), params).toString();
         }
         /** Returns the command header text as a string. Header text can be zero or more lines, and can be specified
          * declaratively with the {@link Command#header()} annotation attribute or programmatically by
          * setting the Help instance's {@link Help#header} field.
          * @param params Arguments referenced by the format specifiers in the header strings
          * @return the header lines combined into a single String (which may be empty)
          */
         public String header(Object... params) {
             return join(ansi(), header, new StringBuilder(), params).toString();
         }
         /** Returns command footer text as a string. Footer text can be zero or more lines, and can be specified
          * declaratively with the {@link Command#footer()} annotation attribute or programmatically by
          * setting the Help instance's {@link Help#footer} field.
          * @param params Arguments referenced by the format specifiers in the footer strings
          * @return the footer lines combined into a single String (which may be empty)
          */
         public String footer(Object... params) {
             return join(ansi(), footer, new StringBuilder(), params).toString();
         }
 
         /** Returns the text displayed before the header text; the result of {@code String.format(headerHeading, params)}.
          * @param params the parameters to use to format the header heading
          * @return the formatted header heading */
         public String headerHeading(Object... params) {
             return heading(ansi(), headerHeading, params);
         }
 
         /** Returns the text displayed before the synopsis text; the result of {@code String.format(synopsisHeading, params)}.
          * @param params the parameters to use to format the synopsis heading
          * @return the formatted synopsis heading */
         public String synopsisHeading(Object... params) {
             return heading(ansi(), synopsisHeading, params);
         }
 
         /** Returns the text displayed before the description text; an empty string if there is no description,
          * otherwise the result of {@code String.format(descriptionHeading, params)}.
          * @param params the parameters to use to format the description heading
          * @return the formatted description heading */
         public String descriptionHeading(Object... params) {
             return empty(descriptionHeading) ? "" : heading(ansi(), descriptionHeading, params);
         }
 
         /** Returns the text displayed before the positional parameter list; an empty string if there are no positional
          * parameters, otherwise the result of {@code String.format(parameterListHeading, params)}.
          * @param params the parameters to use to format the parameter list heading
          * @return the formatted parameter list heading */
         public String parameterListHeading(Object... params) {
             return positionalParametersFields.isEmpty() ? "" : heading(ansi(), parameterListHeading, params);
         }
 
         /** Returns the text displayed before the option list; an empty string if there are no options,
          * otherwise the result of {@code String.format(optionListHeading, params)}.
          * @param params the parameters to use to format the option list heading
          * @return the formatted option list heading */
         public String optionListHeading(Object... params) {
             return optionFields.isEmpty() ? "" : heading(ansi(), optionListHeading, params);
         }
 
         /** Returns the text displayed before the command list; an empty string if there are no commands,
          * otherwise the result of {@code String.format(commandListHeading, params)}.
          * @param params the parameters to use to format the command list heading
          * @return the formatted command list heading */
         public String commandListHeading(Object... params) {
             return commands.isEmpty() ? "" : heading(ansi(), commandListHeading, params);
         }
 
         /** Returns the text displayed before the footer text; the result of {@code String.format(footerHeading, params)}.
          * @param params the parameters to use to format the footer heading
          * @return the formatted footer heading */
         public String footerHeading(Object... params) {
             return heading(ansi(), footerHeading, params);
         }
         /** Returns a 2-column list with command names and the first line of their header or (if absent) description.
          * @return a usage help section describing the added commands */
         public String commandList() {
             if (commands.isEmpty()) { return ""; }
             int commandLength = maxLength(commands.keySet());
             Help.TextTable textTable = new Help.TextTable(ansi(),
                     new Help.Column(commandLength + 2, 2, Help.Column.Overflow.SPAN),
                     new Help.Column(usageHelpWidth - (commandLength + 2), 2, Help.Column.Overflow.WRAP));
 
             for (Map.Entry<String, Help> entry : commands.entrySet()) {
                 Help command = entry.getValue();
                 String header = command.header != null && command.header.length > 0 ? command.header[0]
                         : (command.description != null && command.description.length > 0 ? command.description[0] : "");
                 textTable.addRowValues(colorScheme.commandText(entry.getKey()), ansi().new Text(header));
             }
             return textTable.toString();
         }
         private static int maxLength(Collection<String> any) {
             List<String> strings = new ArrayList<String>(any);
             Collections.sort(strings, Collections.reverseOrder(Help.shortestFirst()));
             return strings.get(0).length();
         }
         private static String join(String[] names, int offset, int length, String separator) {
             if (names == null) { return ""; }
             StringBuilder result = new StringBuilder();
             for (int i = offset; i < offset + length; i++) {
                 result.append((i > offset) ? separator : "").append(names[i]);
             }
             return result.toString();
         }
         private static String stringOf(char chr, int length) {
             char[] buff = new char[length];
             Arrays.fill(buff, chr);
             return new String(buff);
         }
 
         /** Returns a {@code Layout} instance configured with the user preferences captured in this Help instance.
          * @return a Layout */
         public Layout createDefaultLayout() {
             return new Layout(colorScheme, new TextTable(colorScheme.ansi()), createDefaultOptionRenderer(), createDefaultParameterRenderer());
         }
         /** Returns a new default OptionRenderer which converts {@link Option Options} to five columns of text to match
          *  the default {@linkplain TextTable TextTable} column layout. The first row of values looks like this:
          * <ol>
          * <li>the required option marker</li>
          * <li>2-character short option name (or empty string if no short option exists)</li>
          * <li>comma separator (only if both short option and long option exist, empty string otherwise)</li>
          * <li>comma-separated string with long option name(s)</li>
          * <li>first element of the {@link Option#description()} array</li>
          * </ol>
          * <p>Following this, there will be one row for each of the remaining elements of the {@link
          *   Option#description()} array, and these rows look like {@code {"", "", "", "", option.description()[i]}}.</p>
          * <p>If configured, this option renderer adds an additional row to display the default field value.</p>
          * @return a new default OptionRenderer
          */
         public IOptionRenderer createDefaultOptionRenderer() {
             DefaultOptionRenderer result = new DefaultOptionRenderer();
             result.requiredMarker = String.valueOf(requiredOptionMarker);
             if (showDefaultValues != null && showDefaultValues.booleanValue()) {
                 result.command = this.command;
             }
             return result;
         }
         /** Returns a new minimal OptionRenderer which converts {@link Option Options} to a single row with two columns
          * of text: an option name and a description. If multiple names or descriptions exist, the first value is used.
          * @return a new minimal OptionRenderer */
         public static IOptionRenderer createMinimalOptionRenderer() {
             return new MinimalOptionRenderer();
         }
 
         /** Returns a new default ParameterRenderer which converts {@link Parameters Parameters} to four columns of
          * text to match the default {@linkplain TextTable TextTable} column layout. The first row of values looks like this:
          * <ol>
          * <li>empty string </li>
          * <li>empty string </li>
          * <li>parameter(s) label as rendered by the {@link IParamLabelRenderer}</li>
          * <li>first element of the {@link Parameters#description()} array</li>
          * </ol>
          * <p>Following this, there will be one row for each of the remaining elements of the {@link
          *   Parameters#description()} array, and these rows look like {@code {"", "", "", param.description()[i]}}.</p>
          * <p>If configured, this parameter renderer adds an additional row to display the default field value.</p>
          * @return a new default ParameterRenderer
          */
         public IParameterRenderer createDefaultParameterRenderer() {
             DefaultParameterRenderer result = new DefaultParameterRenderer();
             result.requiredMarker = String.valueOf(requiredOptionMarker);
             return result;
         }
         /** Returns a new minimal ParameterRenderer which converts {@link Parameters Parameters} to a single row with
          * two columns of text: an option name and a description. If multiple descriptions exist, the first value is used.
          * @return a new minimal ParameterRenderer */
         public static IParameterRenderer createMinimalParameterRenderer() {
             return new MinimalParameterRenderer();
         }
 
         /** Returns a value renderer that returns the {@code paramLabel} if defined or the field name otherwise.
          * @return a new minimal ParamLabelRenderer */
         public static IParamLabelRenderer createMinimalParamLabelRenderer() {
             return new IParamLabelRenderer() {
                 public Text renderParameterLabel(Field field, Ansi ansi, List<IStyle> styles) {
                     String text = DefaultParamLabelRenderer.renderParameterName(field);
                     return ansi.apply(text, styles);
                 }
                 public String separator() { return ""; }
             };
         }
         /** Returns a new default value renderer that separates option parameters from their {@linkplain Option
          * options} with the specified separator string, surrounds optional parameters with {@code '['} and {@code ']'}
          * characters and uses ellipses ("...") to indicate that any number of a parameter are allowed.
          * @return a new default ParamLabelRenderer
          */
         public IParamLabelRenderer createDefaultParamLabelRenderer() {
             return new DefaultParamLabelRenderer(separator);
         }
         /** Sorts Fields annotated with {@code Option} by their option name in case-insensitive alphabetic order. If an
          * Option has multiple names, the shortest name is used for the sorting. Help options follow non-help options.
          * @return a comparator that sorts fields by their option name in case-insensitive alphabetic order */
         public static Comparator<Field> createShortOptionNameComparator() {
             return new SortByShortestOptionNameAlphabetically();
         }
         /** Sorts Fields annotated with {@code Option} by their option {@linkplain Range#max max arity} first, by
          * {@linkplain Range#min min arity} next, and by {@linkplain #createShortOptionNameComparator() option name} last.
          * @return a comparator that sorts fields by arity first, then their option name */
         public static Comparator<Field> createShortOptionArityAndNameComparator() {
             return new SortByOptionArityAndNameAlphabetically();
         }
         /** Sorts short strings before longer strings.
          * @return a comparators that sorts short strings before longer strings */
         public static Comparator<String> shortestFirst() {
             return new ShortestFirst();
         }
 
         /** Returns whether ANSI escape codes are enabled or not.
          * @return whether ANSI escape codes are enabled or not
          */
         public Ansi ansi() {
             return colorScheme.ansi;
         }
 
         /** When customizing online help for {@link Option Option} details, a custom {@code IOptionRenderer} can be
          * used to create textual representation of an Option in a tabular format: one or more rows, each containing
          * one or more columns. The {@link Layout Layout} is responsible for placing these text values in the
          * {@link TextTable TextTable}. */
         public interface IOptionRenderer {
             /**
              * Returns a text representation of the specified Option and the Field that captures the option value.
              * @param option the command line option to show online usage help for
              * @param field the field that will hold the value for the command line option
              * @param parameterLabelRenderer responsible for rendering option parameters to text
              * @param scheme color scheme for applying ansi color styles to options and option parameters
              * @return a 2-dimensional array of text values: one or more rows, each containing one or more columns
              */
             Text[][] render(Option option, Field field, IParamLabelRenderer parameterLabelRenderer, ColorScheme scheme);
         }
         /** The DefaultOptionRenderer converts {@link Option Options} to five columns of text to match the default
          * {@linkplain TextTable TextTable} column layout. The first row of values looks like this:
          * <ol>
          * <li>the required option marker (if the option is required)</li>
          * <li>2-character short option name (or empty string if no short option exists)</li>
          * <li>comma separator (only if both short option and long option exist, empty string otherwise)</li>
          * <li>comma-separated string with long option name(s)</li>
          * <li>first element of the {@link Option#description()} array</li>
          * </ol>
          * <p>Following this, there will be one row for each of the remaining elements of the {@link
          *   Option#description()} array, and these rows look like {@code {"", "", "", option.description()[i]}}.</p>
          */
         static class DefaultOptionRenderer implements IOptionRenderer {
             public String requiredMarker = " ";
             public Object command;
             private String sep;
             private boolean showDefault;
             public Text[][] render(Option option, Field field, IParamLabelRenderer paramLabelRenderer, ColorScheme scheme) {
                 String[] names = ShortestFirst.sort(option.names());
                 int shortOptionCount = names[0].length() == 2 ? 1 : 0;
                 String shortOption = shortOptionCount > 0 ? names[0] : "";
                 sep = shortOptionCount > 0 && names.length > 1 ? "," : "";
 
                 String longOption = join(names, shortOptionCount, names.length - shortOptionCount, ", ");
                 Text longOptionText = createLongOptionText(field, paramLabelRenderer, scheme, longOption);
 
                 showDefault = command != null && !option.help() && !isBoolean(field.getType());
                 Object defaultValue = createDefaultValue(field);
 
                 String requiredOption = option.required() ? requiredMarker : "";
                 return renderDescriptionLines(option, scheme, requiredOption, shortOption, longOptionText, defaultValue);
             }
 
             private Object createDefaultValue(Field field) {
                 Object defaultValue = null;
                 try {
                     defaultValue = field.get(command);
                     if (defaultValue == null) { showDefault = false; } // #201 don't show null default values
                     else if (field.getType().isArray()) {
                         StringBuilder sb = new StringBuilder();
                         for (int i = 0; i < Array.getLength(defaultValue); i++) {
                             sb.append(i > 0 ? ", " : "").append(Array.get(defaultValue, i));
                         }
                         defaultValue = sb.insert(0, "[").append("]").toString();
                     }
                 } catch (Exception ex) {
                     showDefault = false;
                 }
                 return defaultValue;
             }
 
             private Text createLongOptionText(Field field, IParamLabelRenderer renderer, ColorScheme scheme, String longOption) {
                 Text paramLabelText = renderer.renderParameterLabel(field, scheme.ansi(), scheme.optionParamStyles);
 
                 // if no long option, fill in the space between the short option name and the param label value
                 if (paramLabelText.length > 0 && longOption.length() == 0) {
                     sep = renderer.separator();
                     // #181 paramLabelText may be =LABEL or [=LABEL...]
                     int sepStart = paramLabelText.plainString().indexOf(sep);
                     Text prefix = paramLabelText.substring(0, sepStart);
                     paramLabelText = prefix.append(paramLabelText.substring(sepStart + sep.length()));
                 }
                 Text longOptionText = scheme.optionText(longOption);
                 longOptionText = longOptionText.append(paramLabelText);
                 return longOptionText;
             }
 
             private Text[][] renderDescriptionLines(Option option,
                                                     ColorScheme scheme,
                                                     String requiredOption,
                                                     String shortOption,
                                                     Text longOptionText,
                                                     Object defaultValue) {
                 Text EMPTY = Ansi.EMPTY_TEXT;
                 List<Text[]> result = new ArrayList<Text[]>();
                 Text[] descriptionFirstLines = scheme.ansi().new Text(str(option.description(), 0)).splitLines();
                 if (descriptionFirstLines.length == 0) {
                     if (showDefault) {
                         descriptionFirstLines = new Text[]{scheme.ansi().new Text("  Default: " + defaultValue)};
                         showDefault = false; // don't show the default value twice
                     } else {
                         descriptionFirstLines = new Text[]{ EMPTY };
                     }
                 }
                 result.add(new Text[] { scheme.optionText(requiredOption), scheme.optionText(shortOption),
                         scheme.ansi().new Text(sep), longOptionText, descriptionFirstLines[0] });
                 for (int i = 1; i < descriptionFirstLines.length; i++) {
                     result.add(new Text[] { EMPTY, EMPTY, EMPTY, EMPTY, descriptionFirstLines[i] });
                 }
                 for (int i = 1; i < option.description().length; i++) {
                     Text[] descriptionNextLines = scheme.ansi().new Text(option.description()[i]).splitLines();
                     for (Text line : descriptionNextLines) {
                         result.add(new Text[] { EMPTY, EMPTY, EMPTY, EMPTY, line });
                     }
                 }
                 if (showDefault) {
                     result.add(new Text[] { EMPTY, EMPTY, EMPTY, EMPTY, scheme.ansi().new Text("  Default: " + defaultValue) });
                 }
                 return result.toArray(new Text[result.size()][]);
             }
         }
         /** The MinimalOptionRenderer converts {@link Option Options} to a single row with two columns of text: an
          * option name and a description. If multiple names or description lines exist, the first value is used. */
         static class MinimalOptionRenderer implements IOptionRenderer {
             public Text[][] render(Option option, Field field, IParamLabelRenderer parameterLabelRenderer, ColorScheme scheme) {
                 Text optionText = scheme.optionText(option.names()[0]);
                 Text paramLabelText = parameterLabelRenderer.renderParameterLabel(field, scheme.ansi(), scheme.optionParamStyles);
                 optionText = optionText.append(paramLabelText);
                 return new Text[][] {{ optionText,
                                         scheme.ansi().new Text(option.description().length == 0 ? "" : option.description()[0]) }};
             }
         }
         /** The MinimalParameterRenderer converts {@link Parameters Parameters} to a single row with two columns of
          * text: the parameters label and a description. If multiple description lines exist, the first value is used. */
         static class MinimalParameterRenderer implements IParameterRenderer {
             public Text[][] render(Parameters param, Field field, IParamLabelRenderer parameterLabelRenderer, ColorScheme scheme) {
                 return new Text[][] {{ parameterLabelRenderer.renderParameterLabel(field, scheme.ansi(), scheme.parameterStyles),
                         scheme.ansi().new Text(param.description().length == 0 ? "" : param.description()[0]) }};
             }
         }
         /** When customizing online help for {@link Parameters Parameters} details, a custom {@code IParameterRenderer}
          * can be used to create textual representation of a Parameters field in a tabular format: one or more rows,
          * each containing one or more columns. The {@link Layout Layout} is responsible for placing these text
          * values in the {@link TextTable TextTable}. */
         public interface IParameterRenderer {
             /**
              * Returns a text representation of the specified Parameters and the Field that captures the parameter values.
              * @param parameters the command line parameters to show online usage help for
              * @param field the field that will hold the value for the command line parameters
              * @param parameterLabelRenderer responsible for rendering parameter labels to text
              * @param scheme color scheme for applying ansi color styles to positional parameters
              * @return a 2-dimensional array of text values: one or more rows, each containing one or more columns
              */
             Text[][] render(Parameters parameters, Field field, IParamLabelRenderer parameterLabelRenderer, ColorScheme scheme);
         }
         /** The DefaultParameterRenderer converts {@link Parameters Parameters} to five columns of text to match the
          * default {@linkplain TextTable TextTable} column layout. The first row of values looks like this:
          * <ol>
          * <li>the required option marker (if the parameter's arity is to have at least one value)</li>
          * <li>empty string </li>
          * <li>empty string </li>
          * <li>parameter(s) label as rendered by the {@link IParamLabelRenderer}</li>
          * <li>first element of the {@link Parameters#description()} array</li>
          * </ol>
          * <p>Following this, there will be one row for each of the remaining elements of the {@link
          *   Parameters#description()} array, and these rows look like {@code {"", "", "", param.description()[i]}}.</p>
          */
         static class DefaultParameterRenderer implements IParameterRenderer {
             public String requiredMarker = " ";
             public Text[][] render(Parameters params, Field field, IParamLabelRenderer paramLabelRenderer, ColorScheme scheme) {
                 Text label = paramLabelRenderer.renderParameterLabel(field, scheme.ansi(), scheme.parameterStyles);
                 Text requiredParameter = scheme.parameterText(Range.parameterArity(field).min > 0 ? requiredMarker : "");
 
                 Text EMPTY = Ansi.EMPTY_TEXT;
                 List<Text[]> result = new ArrayList<Text[]>();
                 Text[] descriptionFirstLines = scheme.ansi().new Text(str(params.description(), 0)).splitLines();
                 if (descriptionFirstLines.length == 0) { descriptionFirstLines = new Text[]{ EMPTY }; }
                 result.add(new Text[] { requiredParameter, EMPTY, EMPTY, label, descriptionFirstLines[0] });
                 for (int i = 1; i < descriptionFirstLines.length; i++) {
                     result.add(new Text[] { EMPTY, EMPTY, EMPTY, EMPTY, descriptionFirstLines[i] });
                 }
                 for (int i = 1; i < params.description().length; i++) {
                     Text[] descriptionNextLines = scheme.ansi().new Text(params.description()[i]).splitLines();
                     for (Text line : descriptionNextLines) {
                         result.add(new Text[] { EMPTY, EMPTY, EMPTY, EMPTY, line });
                     }
                 }
                 return result.toArray(new Text[result.size()][]);
             }
         }
         /** When customizing online usage help for an option parameter or a positional parameter, a custom
          * {@code IParamLabelRenderer} can be used to render the parameter name or label to a String. */
         public interface IParamLabelRenderer {
 
             /** Returns a text rendering of the Option parameter or positional parameter; returns an empty string
              * {@code ""} if the option is a boolean and does not take a parameter.
              * @param field the annotated field with a parameter label
              * @param ansi determines whether ANSI escape codes should be emitted or not
              * @param styles the styles to apply to the parameter label
              * @return a text rendering of the Option parameter or positional parameter */
             Text renderParameterLabel(Field field, Ansi ansi, List<IStyle> styles);
 
             /** Returns the separator between option name and param label.
              * @return the separator between option name and param label */
             String separator();
         }
         /**
          * DefaultParamLabelRenderer separates option parameters from their {@linkplain Option options} with a
          * {@linkplain DefaultParamLabelRenderer#separator separator} string, surrounds optional values
          * with {@code '['} and {@code ']'} characters and uses ellipses ("...") to indicate that any number of
          * values is allowed for options or parameters with variable arity.
          */
         static class DefaultParamLabelRenderer implements IParamLabelRenderer {
             /** The string to use to separate option parameters from their options. */
             public final String separator;
             /** Constructs a new DefaultParamLabelRenderer with the specified separator string. */
             public DefaultParamLabelRenderer(String separator) {
                 this.separator = Assert.notNull(separator, "separator");
             }
             public String separator() { return separator; }
             public Text renderParameterLabel(Field field, Ansi ansi, List<IStyle> styles) {
                 boolean isOptionParameter = field.isAnnotationPresent(Option.class);
                 Range arity = isOptionParameter ? Range.optionArity(field) : Range.parameterCapacity(field);
                 String split = isOptionParameter ? field.getAnnotation(Option.class).split() : field.getAnnotation(Parameters.class).split();
                 Text result = ansi.new Text("");
                 String sep = isOptionParameter ? separator : "";
                 Text paramName = ansi.apply(renderParameterName(field), styles);
                 if (!empty(split)) { paramName = paramName.append("[" + split).append(paramName).append("]..."); } // #194
                 for (int i = 0; i < arity.min; i++) {
                     result = result.append(sep).append(paramName);
                     sep = " ";
                 }
                 if (arity.isVariable) {
                     if (result.length == 0) { // arity="*" or arity="0..*"
                         result = result.append(sep + "[").append(paramName).append("]...");
                     } else if (!result.plainString().endsWith("...")) { // split param may already end with "..."
                         result = result.append("...");
                     }
                 } else {
                     sep = result.length == 0 ? (isOptionParameter ? separator : "") : " ";
                     for (int i = arity.min; i < arity.max; i++) {
                         if (sep.trim().length() == 0) {
                             result = result.append(sep + "[").append(paramName);
                         } else {
                             result = result.append("[" + sep).append(paramName);
                         }
                         sep  = " ";
                     }
                     for (int i = arity.min; i < arity.max; i++) { result = result.append("]"); }
                 }
                 return result;
             }
             private static String renderParameterName(Field field) {
                 String result = null;
                 if (field.isAnnotationPresent(Option.class)) {
                     result = field.getAnnotation(Option.class).paramLabel();
                 } else if (field.isAnnotationPresent(Parameters.class)) {
                     result = field.getAnnotation(Parameters.class).paramLabel();
                 }
                 if (result != null && result.trim().length() > 0) {
                     return result.trim();
                 }
                 String name = field.getName();
                 if (Map.class.isAssignableFrom(field.getType())) { // #195 better param labels for map fields
                     Class<?>[] paramTypes = getTypeAttribute(field);
                     if (paramTypes.length < 2 || paramTypes[0] == null || paramTypes[1] == null) {
                         name = "String=String";
                     } else { name = paramTypes[0].getSimpleName() + "=" + paramTypes[1].getSimpleName(); }
                 }
                 return "<" + name + ">";
             }
         }
         /** Use a Layout to format usage help text for options and parameters in tabular format.
          * <p>Delegates to the renderers to create {@link Text} values for the annotated fields, and uses a
          * {@link TextTable} to display these values in tabular format. Layout is responsible for deciding which values
          * to display where in the table. By default, Layout shows one option or parameter per table row.</p>
          * <p>Customize by overriding the {@link #layout(Field, CommandLine.Help.Ansi.Text[][])} method.</p>
          * @see IOptionRenderer rendering options to text
          * @see IParameterRenderer rendering parameters to text
          * @see TextTable showing values in a tabular format
          */
         public static class Layout {
             protected final ColorScheme colorScheme;
             protected final TextTable table;
             protected IOptionRenderer optionRenderer;
             protected IParameterRenderer parameterRenderer;
 
             /** Constructs a Layout with the specified color scheme, a new default TextTable, the
              * {@linkplain Help#createDefaultOptionRenderer() default option renderer}, and the
              * {@linkplain Help#createDefaultParameterRenderer() default parameter renderer}.
              * @param colorScheme the color scheme to use for common, auto-generated parts of the usage help message */
             public Layout(ColorScheme colorScheme) { this(colorScheme, new TextTable(colorScheme.ansi())); }
 
             /** Constructs a Layout with the specified color scheme, the specified TextTable, the
              * {@linkplain Help#createDefaultOptionRenderer() default option renderer}, and the
              * {@linkplain Help#createDefaultParameterRenderer() default parameter renderer}.
              * @param colorScheme the color scheme to use for common, auto-generated parts of the usage help message
              * @param textTable the TextTable to lay out parts of the usage help message in tabular format */
             public Layout(ColorScheme colorScheme, TextTable textTable) {
                 this(colorScheme, textTable, new DefaultOptionRenderer(), new DefaultParameterRenderer());
             }
             /** Constructs a Layout with the specified color scheme, the specified TextTable, the
              * specified option renderer and the specified parameter renderer.
              * @param colorScheme the color scheme to use for common, auto-generated parts of the usage help message
              * @param optionRenderer the object responsible for rendering Options to Text
              * @param parameterRenderer the object responsible for rendering Parameters to Text
              * @param textTable the TextTable to lay out parts of the usage help message in tabular format */
             public Layout(ColorScheme colorScheme, TextTable textTable, IOptionRenderer optionRenderer, IParameterRenderer parameterRenderer) {
                 this.colorScheme       = Assert.notNull(colorScheme, "colorScheme");
                 this.table             = Assert.notNull(textTable, "textTable");
                 this.optionRenderer    = Assert.notNull(optionRenderer, "optionRenderer");
                 this.parameterRenderer = Assert.notNull(parameterRenderer, "parameterRenderer");
             }
             /**
              * Copies the specified text values into the correct cells in the {@link TextTable}. This implementation
              * delegates to {@link TextTable#addRowValues(CommandLine.Help.Ansi.Text...)} for each row of values.
              * <p>Subclasses may override.</p>
              * @param field the field annotated with the specified Option or Parameters
              * @param cellValues the text values representing the Option/Parameters, to be displayed in tabular form
              */
             public void layout(Field field, Text[][] cellValues) {
                 for (Text[] oneRow : cellValues) {
                     table.addRowValues(oneRow);
                 }
             }
             /** Calls {@link #addOption(Field, CommandLine.Help.IParamLabelRenderer)} for all non-hidden Options in the list.
              * @param fields fields annotated with {@link Option} to add usage descriptions for
              * @param paramLabelRenderer object that knows how to render option parameters */
             public void addOptions(List<Field> fields, IParamLabelRenderer paramLabelRenderer) {
                 for (Field field : fields) {
                     Option option = field.getAnnotation(Option.class);
                     if (!option.hidden()) {
                         addOption(field, paramLabelRenderer);
                     }
                 }
             }
             /**
              * Delegates to the {@link #optionRenderer option renderer} of this layout to obtain
              * text values for the specified {@link Option}, and then calls the {@link #layout(Field, CommandLine.Help.Ansi.Text[][])}
              * method to write these text values into the correct cells in the TextTable.
              * @param field the field annotated with the specified Option
              * @param paramLabelRenderer knows how to render option parameters
              */
             public void addOption(Field field, IParamLabelRenderer paramLabelRenderer) {
                 Option option = field.getAnnotation(Option.class);
                 Text[][] values = optionRenderer.render(option, field, paramLabelRenderer, colorScheme);
                 layout(field, values);
             }
             /** Calls {@link #addPositionalParameter(Field, CommandLine.Help.IParamLabelRenderer)} for all non-hidden Parameters in the list.
              * @param fields fields annotated with {@link Parameters} to add usage descriptions for
              * @param paramLabelRenderer knows how to render option parameters */
             public void addPositionalParameters(List<Field> fields, IParamLabelRenderer paramLabelRenderer) {
                 for (Field field : fields) {
                     Parameters parameters = field.getAnnotation(Parameters.class);
                     if (!parameters.hidden()) {
                         addPositionalParameter(field, paramLabelRenderer);
                     }
                 }
             }
             /**
              * Delegates to the {@link #parameterRenderer parameter renderer} of this layout
              * to obtain text values for the specified {@link Parameters}, and then calls
              * {@link #layout(Field, CommandLine.Help.Ansi.Text[][])} to write these text values into the correct cells in the TextTable.
              * @param field the field annotated with the specified Parameters
              * @param paramLabelRenderer knows how to render option parameters
              */
             public void addPositionalParameter(Field field, IParamLabelRenderer paramLabelRenderer) {
                 Parameters option = field.getAnnotation(Parameters.class);
                 Text[][] values = parameterRenderer.render(option, field, paramLabelRenderer, colorScheme);
                 layout(field, values);
             }
             /** Returns the section of the usage help message accumulated in the TextTable owned by this layout. */
             @Override public String toString() {
                 return table.toString();
             }
         }
         /** Sorts short strings before longer strings. */
         static class ShortestFirst implements Comparator<String> {
             public int compare(String o1, String o2) {
                 return o1.length() - o2.length();
             }
             /** Sorts the specified array of Strings shortest-first and returns it. */
             public static String[] sort(String[] names) {
                 Arrays.sort(names, new ShortestFirst());
                 return names;
             }
         }
         /** Sorts {@code Option} instances by their name in case-insensitive alphabetic order. If an Option has
          * multiple names, the shortest name is used for the sorting. Help options follow non-help options. */
         static class SortByShortestOptionNameAlphabetically implements Comparator<Field> {
             public int compare(Field f1, Field f2) {
                 Option o1 = f1.getAnnotation(Option.class);
                 Option o2 = f2.getAnnotation(Option.class);
                 if (o1 == null) { return 1; } else if (o2 == null) { return -1; } // options before params
                 String[] names1 = ShortestFirst.sort(o1.names());
                 String[] names2 = ShortestFirst.sort(o2.names());
                 int result = names1[0].toUpperCase().compareTo(names2[0].toUpperCase()); // case insensitive sort
                 result = result == 0 ? -names1[0].compareTo(names2[0]) : result; // lower case before upper case
                 return o1.help() == o2.help() ? result : o2.help() ? -1 : 1; // help options come last
             }
         }
         /** Sorts {@code Option} instances by their max arity first, then their min arity, then delegates to super class. */
         static class SortByOptionArityAndNameAlphabetically extends SortByShortestOptionNameAlphabetically {
             public int compare(Field f1, Field f2) {
                 Option o1 = f1.getAnnotation(Option.class);
                 Option o2 = f2.getAnnotation(Option.class);
                 Range arity1 = Range.optionArity(f1);
                 Range arity2 = Range.optionArity(f2);
                 int result = arity1.max - arity2.max;
                 if (result == 0) {
                     result = arity1.min - arity2.min;
                 }
                 if (result == 0) { // arity is same
                     if (isMultiValue(f1) && !isMultiValue(f2)) { result = 1; } // f1 > f2
                     if (!isMultiValue(f1) && isMultiValue(f2)) { result = -1; } // f1 < f2
                 }
                 return result == 0 ? super.compare(f1, f2) : result;
             }
         }
         /**
          * <p>Responsible for spacing out {@link Text} values according to the {@link Column} definitions the table was
          * created with. Columns have a width, indentation, and an overflow policy that decides what to do if a value is
          * longer than the column's width.</p>
          */
         public static class TextTable {
             /**
              * Helper class to index positions in a {@code Help.TextTable}.
              * @since 2.0
              */
             public static class Cell {
                 /** Table column index (zero based). */
                 public final int column;
                 /** Table row index (zero based). */
                 public final int row;
                 /** Constructs a new Cell with the specified coordinates in the table.
                  * @param column the zero-based table column
                  * @param row the zero-based table row */
                 public Cell(int column, int row) { this.column = column; this.row = row; }
             }
 
             /** The column definitions of this table. */
             public final Column[] columns;
 
             /** The {@code char[]} slots of the {@code TextTable} to copy text values into. */
             protected final List<Text> columnValues = new ArrayList<Text>();
 
             /** By default, indent wrapped lines by 2 spaces. */
             public int indentWrappedLines = 2;
 
             private final Ansi ansi;
 
             /** Constructs a TextTable with five columns as follows:
              * <ol>
              * <li>required option/parameter marker (width: 2, indent: 0, TRUNCATE on overflow)</li>
              * <li>short option name (width: 2, indent: 0, TRUNCATE on overflow)</li>
              * <li>comma separator (width: 1, indent: 0, TRUNCATE on overflow)</li>
              * <li>long option name(s) (width: 24, indent: 1, SPAN multiple columns on overflow)</li>
              * <li>description line(s) (width: 51, indent: 1, WRAP to next row on overflow)</li>
              * </ol>
              * @param ansi whether to emit ANSI escape codes or not
              */
             public TextTable(Ansi ansi) {
                 // "* -c, --create                Creates a ...."
                 this(ansi, new Column[] {
                             new Column(2,                                        0, TRUNCATE), // "*"
                             new Column(2,                                        0, TRUNCATE), // "-c"
                             new Column(1,                                        0, TRUNCATE), // ","
                             new Column(optionsColumnWidth - 2 - 2 - 1       , 1, SPAN),  // " --create"
                             new Column(usageHelpWidth - optionsColumnWidth, 1, WRAP) // " Creates a ..."
                     });
             }
 
             /** Constructs a new TextTable with columns with the specified width, all SPANning  multiple columns on
              * overflow except the last column which WRAPS to the next row.
              * @param ansi whether to emit ANSI escape codes or not
              * @param columnWidths the width of the table columns (all columns have zero indent)
              */
             public TextTable(Ansi ansi, int... columnWidths) {
                 this.ansi = Assert.notNull(ansi, "ansi");
                 columns = new Column[columnWidths.length];
                 for (int i = 0; i < columnWidths.length; i++) {
                     columns[i] = new Column(columnWidths[i], 0, i == columnWidths.length - 1 ? SPAN: WRAP);
                 }
             }
             /** Constructs a {@code TextTable} with the specified columns.
              * @param ansi whether to emit ANSI escape codes or not
              * @param columns columns to construct this TextTable with */
             public TextTable(Ansi ansi, Column... columns) {
                 this.ansi = Assert.notNull(ansi, "ansi");
                 this.columns = Assert.notNull(columns, "columns");
                 if (columns.length == 0) { throw new IllegalArgumentException("At least one column is required"); }
             }
             /** Returns the {@code Text} slot at the specified row and column to write a text value into.
              * @param row the row of the cell whose Text to return
              * @param col the column of the cell whose Text to return
              * @return the Text object at the specified row and column
              * @since 2.0 */
             public Text textAt(int row, int col) { return columnValues.get(col + (row * columns.length)); }
 
             /** Returns the {@code Text} slot at the specified row and column to write a text value into.
              * @param row the row of the cell whose Text to return
              * @param col the column of the cell whose Text to return
              * @return the Text object at the specified row and column
              * @deprecated use {@link #textAt(int, int)} instead */
             public Text cellAt(int row, int col) { return textAt(row, col); }
 
             /** Returns the current number of rows of this {@code TextTable}.
              * @return the current number of rows in this TextTable */
             public int rowCount() { return columnValues.size() / columns.length; }
 
             /** Adds the required {@code char[]} slots for a new row to the {@link #columnValues} field. */
             public void addEmptyRow() {
                 for (int i = 0; i < columns.length; i++) {
                     columnValues.add(ansi.new Text(columns[i].width));
                 }
             }
 
             /** Delegates to {@link #addRowValues(CommandLine.Help.Ansi.Text...)}.
              * @param values the text values to display in each column of the current row */
             public void addRowValues(String... values) {
                 Text[] array = new Text[values.length];
                 for (int i = 0; i < array.length; i++) {
                     array[i] = values[i] == null ? Ansi.EMPTY_TEXT : ansi.new Text(values[i]);
                 }
                 addRowValues(array);
             }
             /**
              * Adds a new {@linkplain TextTable#addEmptyRow() empty row}, then calls {@link
              * TextTable#putValue(int, int, CommandLine.Help.Ansi.Text) putValue} for each of the specified values, adding more empty rows
              * if the return value indicates that the value spanned multiple columns or was wrapped to multiple rows.
              * @param values the values to write into a new row in this TextTable
              * @throws IllegalArgumentException if the number of values exceeds the number of Columns in this table
              */
             public void addRowValues(Text... values) {
                 if (values.length > columns.length) {
                     throw new IllegalArgumentException(values.length + " values don't fit in " +
                             columns.length + " columns");
                 }
                 addEmptyRow();
                 for (int col = 0; col < values.length; col++) {
                     int row = rowCount() - 1;// write to last row: previous value may have wrapped to next row
                     Cell cell = putValue(row, col, values[col]);
 
                     // add row if a value spanned/wrapped and there are still remaining values
                     if ((cell.row != row || cell.column != col) && col != values.length - 1) {
                         addEmptyRow();
                     }
                 }
             }
             /**
              * Writes the specified value into the cell at the specified row and column and returns the last row and
              * column written to. Depending on the Column's {@link Column#overflow Overflow} policy, the value may span
              * multiple columns or wrap to multiple rows when larger than the column width.
              * @param row the target row in the table
              * @param col the target column in the table to write to
              * @param value the value to write
              * @return a Cell indicating the position in the table that was last written to (since 2.0)
              * @throws IllegalArgumentException if the specified row exceeds the table's {@linkplain
              *          TextTable#rowCount() row count}
              * @since 2.0 (previous versions returned a {@code java.awt.Point} object)
              */
             public Cell putValue(int row, int col, Text value) {
                 if (row > rowCount() - 1) {
                     throw new IllegalArgumentException("Cannot write to row " + row + ": rowCount=" + rowCount());
                 }
                 if (value == null || value.plain.length() == 0) { return new Cell(col, row); }
                 Column column = columns[col];
                 int indent = column.indent;
                 switch (column.overflow) {
                     case TRUNCATE:
                         copy(value, textAt(row, col), indent);
                         return new Cell(col, row);
                     case SPAN:
                         int startColumn = col;
                         do {
                             boolean lastColumn = col == columns.length - 1;
                             int charsWritten = lastColumn
                                     ? copy(BreakIterator.getLineInstance(), value, textAt(row, col), indent)
                                     : copy(value, textAt(row, col), indent);
                             value = value.substring(charsWritten);
                             indent = 0;
                             if (value.length > 0) { // value did not fit in column
                                 ++col;                // write remainder of value in next column
                             }
                             if (value.length > 0 && col >= columns.length) { // we filled up all columns on this row
                                 addEmptyRow();
                                 row++;
                                 col = startColumn;
                                 indent = column.indent + indentWrappedLines;
                             }
                         } while (value.length > 0);
                         return new Cell(col, row);
                     case WRAP:
                         BreakIterator lineBreakIterator = BreakIterator.getLineInstance();
                         do {
                             int charsWritten = copy(lineBreakIterator, value, textAt(row, col), indent);
                             value = value.substring(charsWritten);
                             indent = column.indent + indentWrappedLines;
                             if (value.length > 0) {  // value did not fit in column
                                 ++row;                 // write remainder of value in next row
                                 addEmptyRow();
                             }
                         } while (value.length > 0);
                         return new Cell(col, row);
                 }
                 throw new IllegalStateException(column.overflow.toString());
             }
             private static int length(Text str) {
                 return str.length; // TODO count some characters as double length
             }
 
             private int copy(BreakIterator line, Text text, Text columnValue, int offset) {
                 // Deceive the BreakIterator to ensure no line breaks after '-' character
                 line.setText(text.plainString().replace("-", "\u00ff"));
                 int done = 0;
                 for (int start = line.first(), end = line.next(); end != BreakIterator.DONE; start = end, end = line.next()) {
                     Text word = text.substring(start, end); //.replace("\u00ff", "-"); // not needed
                     if (columnValue.maxLength >= offset + done + length(word)) {
                         done += copy(word, columnValue, offset + done); // TODO localized length
                     } else {
                         break;
                     }
                 }
                 if (done == 0 && length(text) > columnValue.maxLength) {
                     // The value is a single word that is too big to be written to the column. Write as much as we can.
                     done = copy(text, columnValue, offset);
                 }
                 return done;
             }
             private static int copy(Text value, Text destination, int offset) {
                 int length = Math.min(value.length, destination.maxLength - offset);
                 value.getStyledChars(value.from, length, destination, offset);
                 return length;
             }
 
             /** Copies the text representation that we built up from the options into the specified StringBuilder.
              * @param text the StringBuilder to write into
              * @return the specified StringBuilder object (to allow method chaining and a more fluid API) */
             public StringBuilder toString(StringBuilder text) {
                 int columnCount = this.columns.length;
                 StringBuilder row = new StringBuilder(usageHelpWidth);
                 for (int i = 0; i < columnValues.size(); i++) {
                     Text column = columnValues.get(i);
                     row.append(column.toString());
                     row.append(new String(spaces(columns[i % columnCount].width - column.length)));
                     if (i % columnCount == columnCount - 1) {
                         int lastChar = row.length() - 1;
                         while (lastChar >= 0 && row.charAt(lastChar) == ' ') {lastChar--;} // rtrim
                         row.setLength(lastChar + 1);
                         text.append(row.toString()).append(System.getProperty("line.separator"));
                         row.setLength(0);
                     }
                 }
                 //if (Ansi.enabled()) { text.append(Style.reset.off()); }
                 return text;
             }
             public String toString() { return toString(new StringBuilder()).toString(); }
         }
         /** Columns define the width, indent (leading number of spaces in a column before the value) and
          * {@linkplain Overflow Overflow} policy of a column in a {@linkplain TextTable TextTable}. */
         public static class Column {
 
             /** Policy for handling text that is longer than the column width:
              *  span multiple columns, wrap to the next row, or simply truncate the portion that doesn't fit. */
             public enum Overflow { TRUNCATE, SPAN, WRAP }
 
             /** Column width in characters */
             public final int width;
 
             /** Indent (number of empty spaces at the start of the column preceding the text value) */
             public final int indent;
 
             /** Policy that determines how to handle values larger than the column width. */
             public final Overflow overflow;
             public Column(int width, int indent, Overflow overflow) {
                 this.width = width;
                 this.indent = indent;
                 this.overflow = Assert.notNull(overflow, "overflow");
             }
         }
 
         /** All usage help message are generated with a color scheme that assigns certain styles and colors to common
          * parts of a usage message: the command name, options, positional parameters and option parameters.
          * Users may customize these styles by creating Help with a custom color scheme.
          * <p>Note that these options and styles may not be rendered if ANSI escape codes are not
          * {@linkplain Ansi#enabled() enabled}.</p>
          * @see Help#defaultColorScheme(Ansi)
          */
         public static class ColorScheme {
             public final List<IStyle> commandStyles = new ArrayList<IStyle>();
             public final List<IStyle> optionStyles = new ArrayList<IStyle>();
             public final List<IStyle> parameterStyles = new ArrayList<IStyle>();
             public final List<IStyle> optionParamStyles = new ArrayList<IStyle>();
             private final Ansi ansi;
 
             /** Constructs a new ColorScheme with {@link Help.Ansi#AUTO}. */
             public ColorScheme() { this(Ansi.AUTO); }
 
             /** Constructs a new ColorScheme with the specified Ansi enabled mode.
              * @param ansi whether to emit ANSI escape codes or not
              */
             public ColorScheme(Ansi ansi) {this.ansi = Assert.notNull(ansi, "ansi"); }
 
             /** Adds the specified styles to the registered styles for commands in this color scheme and returns this color scheme.
              * @param styles the styles to add to the registered styles for commands in this color scheme
              * @return this color scheme to enable method chaining for a more fluent API */
             public ColorScheme commands(IStyle... styles)     { return addAll(commandStyles, styles); }
             /** Adds the specified styles to the registered styles for options in this color scheme and returns this color scheme.
              * @param styles the styles to add to registered the styles for options in this color scheme
              * @return this color scheme to enable method chaining for a more fluent API */
             public ColorScheme options(IStyle... styles)      { return addAll(optionStyles, styles);}
             /** Adds the specified styles to the registered styles for positional parameters in this color scheme and returns this color scheme.
              * @param styles the styles to add to registered the styles for parameters in this color scheme
              * @return this color scheme to enable method chaining for a more fluent API */
             public ColorScheme parameters(IStyle... styles)   { return addAll(parameterStyles, styles);}
             /** Adds the specified styles to the registered styles for option parameters in this color scheme and returns this color scheme.
              * @param styles the styles to add to the registered styles for option parameters in this color scheme
              * @return this color scheme to enable method chaining for a more fluent API */
             public ColorScheme optionParams(IStyle... styles) { return addAll(optionParamStyles, styles);}
             /** Returns a Text with all command styles applied to the specified command string.
              * @param command the command string to apply the registered command styles to
              * @return a Text with all command styles applied to the specified command string */
             public Ansi.Text commandText(String command)         { return ansi().apply(command,     commandStyles); }
             /** Returns a Text with all option styles applied to the specified option string.
              * @param option the option string to apply the registered option styles to
              * @return a Text with all option styles applied to the specified option string */
             public Ansi.Text optionText(String option)           { return ansi().apply(option,      optionStyles); }
             /** Returns a Text with all parameter styles applied to the specified parameter string.
              * @param parameter the parameter string to apply the registered parameter styles to
              * @return a Text with all parameter styles applied to the specified parameter string */
             public Ansi.Text parameterText(String parameter)     { return ansi().apply(parameter,   parameterStyles); }
             /** Returns a Text with all optionParam styles applied to the specified optionParam string.
              * @param optionParam the option parameter string to apply the registered option parameter styles to
              * @return a Text with all option parameter styles applied to the specified option parameter string */
             public Ansi.Text optionParamText(String optionParam) { return ansi().apply(optionParam, optionParamStyles); }
 
             /** Replaces colors and styles in this scheme with ones specified in system properties, and returns this scheme.
              * Supported property names:<ul>
              *     <li>{@code picocli.color.commands}</li>
              *     <li>{@code picocli.color.options}</li>
              *     <li>{@code picocli.color.parameters}</li>
              *     <li>{@code picocli.color.optionParams}</li>
              * </ul><p>Property values can be anything that {@link Help.Ansi.Style#parse(String)} can handle.</p>
              * @return this ColorScheme
              */
             public ColorScheme applySystemProperties() {
                 replace(commandStyles,     System.getProperty("picocli.color.commands"));
                 replace(optionStyles,      System.getProperty("picocli.color.options"));
                 replace(parameterStyles,   System.getProperty("picocli.color.parameters"));
                 replace(optionParamStyles, System.getProperty("picocli.color.optionParams"));
                 return this;
             }
             private void replace(List<IStyle> styles, String property) {
                 if (property != null) {
                     styles.clear();
                     addAll(styles, Style.parse(property));
                 }
             }
             private ColorScheme addAll(List<IStyle> styles, IStyle... add) {
                 styles.addAll(Arrays.asList(add));
                 return this;
             }
 
             public Ansi ansi() {
                 return ansi;
             }
         }
 
         /** Creates and returns a new {@link ColorScheme} initialized with picocli default values: commands are bold,
          *  options and parameters use a yellow foreground, and option parameters use italic.
          * @param ansi whether the usage help message should contain ANSI escape codes or not
          * @return a new default color scheme
          */
         public static ColorScheme defaultColorScheme(Ansi ansi) {
             return new ColorScheme(ansi)
                     .commands(Style.bold)
                     .options(Style.fg_yellow)
                     .parameters(Style.fg_yellow)
                     .optionParams(Style.italic);
         }
 
         /** Provides methods and inner classes to support using ANSI escape codes in usage help messages. */
         public enum Ansi {
             /** Only emit ANSI escape codes if the platform supports it and system property {@code "picocli.ansi"}
              * is not set to any value other than {@code "true"} (case insensitive). */
             AUTO,
             /** Forced ON: always emit ANSI escape code regardless of the platform. */
             ON,
             /** Forced OFF: never emit ANSI escape code regardless of the platform. */
             OFF;
             static Text EMPTY_TEXT = OFF.new Text(0);
             static final boolean isWindows  = System.getProperty("os.name").startsWith("Windows");
             static final boolean isXterm    = System.getenv("TERM") != null && System.getenv("TERM").startsWith("xterm");
             static final boolean ISATTY = calcTTY();
 
             // http://stackoverflow.com/questions/1403772/how-can-i-check-if-a-java-programs-input-output-streams-are-connected-to-a-term
             static final boolean calcTTY() {
                 if (isWindows && isXterm) { return true; } // Cygwin uses pseudo-tty and console is always null...
                 try { return System.class.getDeclaredMethod("console").invoke(null) != null; }
                 catch (Throwable reflectionFailed) { return true; }
             }
             private static boolean ansiPossible() { return ISATTY && (!isWindows || isXterm); }
 
             /** Returns {@code true} if ANSI escape codes should be emitted, {@code false} otherwise.
              * @return ON: {@code true}, OFF: {@code false}, AUTO: if system property {@code "picocli.ansi"} is
              *      defined then return its boolean value, otherwise return whether the platform supports ANSI escape codes */
             public boolean enabled() {
                 if (this == ON)  { return true; }
                 if (this == OFF) { return false; }
                 return (System.getProperty("picocli.ansi") == null ? ansiPossible() : Boolean.getBoolean("picocli.ansi"));
             }
 
             /** Defines the interface for an ANSI escape sequence. */
             public interface IStyle {
 
                 /** The Control Sequence Introducer (CSI) escape sequence {@value}. */
                 String CSI = "\u001B[";
 
                 /** Returns the ANSI escape code for turning this style on.
                  * @return the ANSI escape code for turning this style on */
                 String on();
 
                 /** Returns the ANSI escape code for turning this style off.
                  * @return the ANSI escape code for turning this style off */
                 String off();
             }
 
             /**
              * A set of pre-defined ANSI escape code styles and colors, and a set of convenience methods for parsing
              * text with embedded markup style names, as well as convenience methods for converting
              * styles to strings with embedded escape codes.
              */
             public enum Style implements IStyle {
                 reset(0, 0), bold(1, 21), faint(2, 22), italic(3, 23), underline(4, 24), blink(5, 25), reverse(7, 27),
                 fg_black(30, 39), fg_red(31, 39), fg_green(32, 39), fg_yellow(33, 39), fg_blue(34, 39), fg_magenta(35, 39), fg_cyan(36, 39), fg_white(37, 39),
                 bg_black(40, 49), bg_red(41, 49), bg_green(42, 49), bg_yellow(43, 49), bg_blue(44, 49), bg_magenta(45, 49), bg_cyan(46, 49), bg_white(47, 49),
                 ;
                 private final int startCode;
                 private final int endCode;
 
                 Style(int startCode, int endCode) {this.startCode = startCode; this.endCode = endCode; }
                 public String on() { return CSI + startCode + "m"; }
                 public String off() { return CSI + endCode + "m"; }
 
 				/** Returns the concatenated ANSI escape codes for turning all specified styles on.
                  * @param styles the styles to generate ANSI escape codes for
                  * @return the concatenated ANSI escape codes for turning all specified styles on */
                 public static String on(IStyle... styles) {
                     StringBuilder result = new StringBuilder();
                     for (IStyle style : styles) {
                         result.append(style.on());
                     }
                     return result.toString();
                 }
 				/** Returns the concatenated ANSI escape codes for turning all specified styles off.
                  * @param styles the styles to generate ANSI escape codes for
                  * @return the concatenated ANSI escape codes for turning all specified styles off */
                 public static String off(IStyle... styles) {
                     StringBuilder result = new StringBuilder();
                     for (IStyle style : styles) {
                         result.append(style.off());
                     }
                     return result.toString();
                 }
 				/** Parses the specified style markup and returns the associated style.
 				 *  The markup may be one of the Style enum value names, or it may be one of the Style enum value
 				 *  names when {@code "fg_"} is prepended, or it may be one of the indexed colors in the 256 color palette.
                  * @param str the case-insensitive style markup to convert, e.g. {@code "blue"} or {@code "fg_blue"},
                  *          or {@code "46"} (indexed color) or {@code "0;5;0"} (RGB components of an indexed color)
 				 * @return the IStyle for the specified converter
 				 */
                 public static IStyle fg(String str) {
                     try { return Style.valueOf(str.toLowerCase(ENGLISH)); } catch (Exception ignored) {}
                     try { return Style.valueOf("fg_" + str.toLowerCase(ENGLISH)); } catch (Exception ignored) {}
                     return new Palette256Color(true, str);
                 }
 				/** Parses the specified style markup and returns the associated style.
 				 *  The markup may be one of the Style enum value names, or it may be one of the Style enum value
 				 *  names when {@code "bg_"} is prepended, or it may be one of the indexed colors in the 256 color palette.
 				 * @param str the case-insensitive style markup to convert, e.g. {@code "blue"} or {@code "bg_blue"},
                  *          or {@code "46"} (indexed color) or {@code "0;5;0"} (RGB components of an indexed color)
 				 * @return the IStyle for the specified converter
 				 */
                 public static IStyle bg(String str) {
                     try { return Style.valueOf(str.toLowerCase(ENGLISH)); } catch (Exception ignored) {}
                     try { return Style.valueOf("bg_" + str.toLowerCase(ENGLISH)); } catch (Exception ignored) {}
                     return new Palette256Color(false, str);
                 }
                 /** Parses the specified comma-separated sequence of style descriptors and returns the associated
                  *  styles. For each markup, strings starting with {@code "bg("} are delegated to
                  *  {@link #bg(String)}, others are delegated to {@link #bg(String)}.
                  * @param commaSeparatedCodes one or more descriptors, e.g. {@code "bg(blue),underline,red"}
                  * @return an array with all styles for the specified descriptors
                  */
                 public static IStyle[] parse(String commaSeparatedCodes) {
                     String[] codes = commaSeparatedCodes.split(",");
                     IStyle[] styles = new IStyle[codes.length];
                     for(int i = 0; i < codes.length; ++i) {
                         if (codes[i].toLowerCase(ENGLISH).startsWith("fg(")) {
                             int end = codes[i].indexOf(')');
                             styles[i] = Style.fg(codes[i].substring(3, end < 0 ? codes[i].length() : end));
                         } else if (codes[i].toLowerCase(ENGLISH).startsWith("bg(")) {
                             int end = codes[i].indexOf(')');
                             styles[i] = Style.bg(codes[i].substring(3, end < 0 ? codes[i].length() : end));
                         } else {
                             styles[i] = Style.fg(codes[i]);
                         }
                     }
                     return styles;
                 }
             }
 
             /** Defines a palette map of 216 colors: 6 * 6 * 6 cube (216 colors):
              * 16 + 36 * r + 6 * g + b (0 &lt;= r, g, b &lt;= 5). */
             static class Palette256Color implements IStyle {
                 private final int fgbg;
                 private final int color;
 
                 Palette256Color(boolean foreground, String color) {
                     this.fgbg = foreground ? 38 : 48;
                     String[] rgb = color.split(";");
                     if (rgb.length == 3) {
                         this.color = 16 + 36 * Integer.decode(rgb[0]) + 6 * Integer.decode(rgb[1]) + Integer.decode(rgb[2]);
                     } else {
                         this.color = Integer.decode(color);
                     }
                 }
                 public String on() { return String.format(CSI + "%d;5;%dm", fgbg, color); }
                 public String off() { return CSI + (fgbg + 1) + "m"; }
             }
             private static class StyledSection {
                 int startIndex, length;
                 String startStyles, endStyles;
                 StyledSection(int start, int len, String style1, String style2) {
                     startIndex = start; length = len; startStyles = style1; endStyles = style2;
                 }
                 StyledSection withStartIndex(int newStart) {
                     return new StyledSection(newStart, length, startStyles, endStyles);
                 }
             }
 
             /**
              * Returns a new Text object where all the specified styles are applied to the full length of the
              * specified plain text.
              * @param plainText the string to apply all styles to. Must not contain markup!
              * @param styles the styles to apply to the full plain text
              * @return a new Text object
              */
             public Text apply(String plainText, List<IStyle> styles) {
                 if (plainText.length() == 0) { return new Text(0); }
                 Text result = new Text(plainText.length());
                 IStyle[] all = styles.toArray(new IStyle[styles.size()]);
                 result.sections.add(new StyledSection(
                         0, plainText.length(), Style.on(all), Style.off(reverse(all)) + Style.reset.off()));
                 result.plain.append(plainText);
                 result.length = result.plain.length();
                 return result;
             }
 
             private static <T> T[] reverse(T[] all) {
                 for (int i = 0; i < all.length / 2; i++) {
                     T temp = all[i];
                     all[i] = all[all.length - i - 1];
                     all[all.length - i - 1] = temp;
                 }
                 return all;
             }
             /** Encapsulates rich text with styles and colors. Text objects may be constructed with Strings containing
              * markup like {@code @|bg(red),white,underline some text|@}, and this class converts the markup to ANSI
              * escape codes.
              * <p>
              * Internally keeps both an enriched and a plain text representation to allow layout components to calculate
              * text width while remaining unaware of the embedded ANSI escape codes.</p> */
             public class Text implements Cloneable {
                 private final int maxLength;
                 private int from;
                 private int length;
                 private StringBuilder plain = new StringBuilder();
                 private List<StyledSection> sections = new ArrayList<StyledSection>();
 
                 /** Constructs a Text with the specified max length (for use in a TextTable Column).
                  * @param maxLength max length of this text */
                 public Text(int maxLength) { this.maxLength = maxLength; }
 
                 /**
                  * Constructs a Text with the specified String, which may contain markup like
                  * {@code @|bg(red),white,underline some text|@}.
                  * @param input the string with markup to parse
                  */
                 public Text(String input) {
                     maxLength = -1;
                     plain.setLength(0);
                     int i = 0;
 
                     while (true) {
                         int j = input.indexOf("@|", i);
                         if (j == -1) {
                             if (i == 0) {
                                 plain.append(input);
                                 length = plain.length();
                                 return;
                             }
                             plain.append(input.substring(i, input.length()));
                             length = plain.length();
                             return;
                         }
                         plain.append(input.substring(i, j));
                         int k = input.indexOf("|@", j);
                         if (k == -1) {
                             plain.append(input);
                             length = plain.length();
                             return;
                         }
 
                         j += 2;
                         String spec = input.substring(j, k);
                         String[] items = spec.split(" ", 2);
                         if (items.length == 1) {
                             plain.append(input);
                             length = plain.length();
                             return;
                         }
 
                         IStyle[] styles = Style.parse(items[0]);
                         addStyledSection(plain.length(), items[1].length(),
                                 Style.on(styles), Style.off(reverse(styles)) + Style.reset.off());
                         plain.append(items[1]);
                         i = k + 2;
                     }
                 }
                 private void addStyledSection(int start, int length, String startStyle, String endStyle) {
                     sections.add(new StyledSection(start, length, startStyle, endStyle));
                 }
                 public Object clone() {
                     try { return super.clone(); } catch (CloneNotSupportedException e) { throw new IllegalStateException(e); }
                 }
 
                 public Text[] splitLines() {
                     List<Text> result = new ArrayList<Text>();
                     boolean trailingEmptyString = false;
                     int start = 0, end = 0;
                     for (int i = 0; i < plain.length(); i++, end = i) {
                         char c = plain.charAt(i);
                         boolean eol = c == '\n';
                         eol |= (c == '\r' && i + 1 < plain.length() && plain.charAt(i + 1) == '\n' && ++i > 0); // \r\n
                         eol |= c == '\r';
                         if (eol) {
                             result.add(this.substring(start, end));
                             trailingEmptyString = i == plain.length() - 1;
                             start = i + 1;
                         }
                     }
                     if (start < plain.length() || trailingEmptyString) {
                         result.add(this.substring(start, plain.length()));
                     }
                     return result.toArray(new Text[result.size()]);
                 }
 
                 /** Returns a new {@code Text} instance that is a substring of this Text. Does not modify this instance!
                  * @param start index in the plain text where to start the substring
                  * @return a new Text instance that is a substring of this Text */
                 public Text substring(int start) {
                     return substring(start, length);
                 }
 
                 /** Returns a new {@code Text} instance that is a substring of this Text. Does not modify this instance!
                  * @param start index in the plain text where to start the substring
                  * @param end index in the plain text where to end the substring
                  * @return a new Text instance that is a substring of this Text */
                 public Text substring(int start, int end) {
                     Text result = (Text) clone();
                     result.from = from + start;
                     result.length = end - start;
                     return result;
                 }
                 /** Returns a new {@code Text} instance with the specified text appended. Does not modify this instance!
                  * @param string the text to append
                  * @return a new Text instance */
                 public Text append(String string) {
                     return append(new Text(string));
                 }
 
                 /** Returns a new {@code Text} instance with the specified text appended. Does not modify this instance!
                  * @param other the text to append
                  * @return a new Text instance */
                 public Text append(Text other) {
                     Text result = (Text) clone();
                     result.plain = new StringBuilder(plain.toString().substring(from, from + length));
                     result.from = 0;
                     result.sections = new ArrayList<StyledSection>();
                     for (StyledSection section : sections) {
                         result.sections.add(section.withStartIndex(section.startIndex - from));
                     }
                     result.plain.append(other.plain.toString().substring(other.from, other.from + other.length));
                     for (StyledSection section : other.sections) {
                         int index = result.length + section.startIndex - other.from;
                         result.sections.add(section.withStartIndex(index));
                     }
                     result.length = result.plain.length();
                     return result;
                 }
 
                 /**
                  * Copies the specified substring of this Text into the specified destination, preserving the markup.
                  * @param from start of the substring
                  * @param length length of the substring
                  * @param destination destination Text to modify
                  * @param offset indentation (padding)
                  */
                 public void getStyledChars(int from, int length, Text destination, int offset) {
                     if (destination.length < offset) {
                         for (int i = destination.length; i < offset; i++) {
                             destination.plain.append(' ');
                         }
                         destination.length = offset;
                     }
                     for (StyledSection section : sections) {
                         destination.sections.add(section.withStartIndex(section.startIndex - from + destination.length));
                     }
                     destination.plain.append(plain.toString().substring(from, from + length));
                     destination.length = destination.plain.length();
                 }
                 /** Returns the plain text without any formatting.
                  * @return the plain text without any formatting */
                 public String plainString() {  return plain.toString().substring(from, from + length); }
 
                 public boolean equals(Object obj) { return toString().equals(String.valueOf(obj)); }
                 public int hashCode() { return toString().hashCode(); }
 
                 /** Returns a String representation of the text with ANSI escape codes embedded, unless ANSI is
                  * {@linkplain Ansi#enabled()} not enabled}, in which case the plain text is returned.
                  * @return a String representation of the text with ANSI escape codes embedded (if enabled) */
                 public String toString() {
                     if (!Ansi.this.enabled()) {
                         return plain.toString().substring(from, from + length);
                     }
                     if (length == 0) { return ""; }
                     StringBuilder sb = new StringBuilder(plain.length() + 20 * sections.size());
                     StyledSection current = null;
                     int end = Math.min(from + length, plain.length());
                     for (int i = from; i < end; i++) {
                         StyledSection section = findSectionContaining(i);
                         if (section != current) {
                             if (current != null) { sb.append(current.endStyles); }
                             if (section != null) { sb.append(section.startStyles); }
                             current = section;
                         }
                         sb.append(plain.charAt(i));
                     }
                     if (current != null) { sb.append(current.endStyles); }
                     return sb.toString();
                 }
 
                 private StyledSection findSectionContaining(int index) {
                     for (StyledSection section : sections) {
                         if (index >= section.startIndex && index < section.startIndex + section.length) {
                             return section;
                         }
                     }
                     return null;
                 }
             }
         }
     }
 
     /**
      * Utility class providing some defensive coding convenience methods.
      */
     private static final class Assert {
         /**
          * Throws a NullPointerException if the specified object is null.
          * @param object the object to verify
          * @param description error message
          * @param <T> type of the object to check
          * @return the verified object
          */
         static <T> T notNull(T object, String description) {
             if (object == null) {
                 throw new NullPointerException(description);
             }
             return object;
         }
         private Assert() {} // private constructor: never instantiate
     }
     private enum TraceLevel { OFF, WARN, INFO, DEBUG;
         public boolean isEnabled(TraceLevel other) { return ordinal() >= other.ordinal(); }
         private void print(Tracer tracer, String msg, Object... params) {
             if (tracer.level.isEnabled(this)) { tracer.stream.printf(prefix(msg), params); }
         }
         private String prefix(String msg) { return "[picocli " + this + "] " + msg; }
         static TraceLevel lookup(String key) { return key == null ? WARN : empty(key) || "true".equalsIgnoreCase(key) ? INFO : valueOf(key); }
     }
     private static class Tracer {
         TraceLevel level = TraceLevel.lookup(System.getProperty("picocli.trace"));
         PrintStream stream = System.err;
         void warn (String msg, Object... params) { TraceLevel.WARN.print(this, msg, params); }
         void info (String msg, Object... params) { TraceLevel.INFO.print(this, msg, params); }
         void debug(String msg, Object... params) { TraceLevel.DEBUG.print(this, msg, params); }
         boolean isWarn()  { return level.isEnabled(TraceLevel.WARN); }
         boolean isInfo()  { return level.isEnabled(TraceLevel.INFO); }
         boolean isDebug() { return level.isEnabled(TraceLevel.DEBUG); }
     }
     /** Base class of all exceptions thrown by {@code picocli.CommandLine}.
      * @since 2.0 */
     public static class PicocliException extends RuntimeException {
         private static final long serialVersionUID = -2574128880125050818L;
         public PicocliException(String msg) { super(msg); }
         public PicocliException(String msg, Exception ex) { super(msg, ex); }
     }
     /** Exception indicating a problem during {@code CommandLine} initialization.
      * @since 2.0 */
     public static class InitializationException extends PicocliException {
         private static final long serialVersionUID = 8423014001666638895L;
         public InitializationException(String msg) { super(msg); }
         public InitializationException(String msg, Exception ex) { super(msg, ex); }
     }
     /** Exception indicating a problem while invoking a command or subcommand.
      * @since 2.0 */
     public static class ExecutionException extends PicocliException {
         private static final long serialVersionUID = 7764539594267007998L;
         private final CommandLine commandLine;
         public ExecutionException(CommandLine commandLine, String msg) {
             super(msg);
             this.commandLine = Assert.notNull(commandLine, "commandLine");
         }
         public ExecutionException(CommandLine commandLine, String msg, Exception ex) {
             super(msg, ex);
             this.commandLine = Assert.notNull(commandLine, "commandLine");
         }
         /** Returns the {@code CommandLine} object for the (sub)command that could not be invoked.
          * @return the {@code CommandLine} object for the (sub)command where invocation failed.
          */
         public CommandLine getCommandLine() { return commandLine; }
     }
 
     /** Exception thrown by {@link ITypeConverter} implementations to indicate a String could not be converted. */
     public static class TypeConversionException extends PicocliException {
         private static final long serialVersionUID = 4251973913816346114L;
         public TypeConversionException(String msg) { super(msg); }
     }
     /** Exception indicating something went wrong while parsing command line options. */
     public static class ParameterException extends PicocliException {
         private static final long serialVersionUID = 1477112829129763139L;
         private final CommandLine commandLine;
 
         /** Constructs a new ParameterException with the specified CommandLine and error message.
          * @param commandLine the command or subcommand whose input was invalid
          * @param msg describes the problem
          * @since 2.0 */
         public ParameterException(CommandLine commandLine, String msg) {
             super(msg);
             this.commandLine = Assert.notNull(commandLine, "commandLine");
         }
         /** Constructs a new ParameterException with the specified CommandLine and error message.
          * @param commandLine the command or subcommand whose input was invalid
          * @param msg describes the problem
          * @param ex the exception that caused this ParameterException
          * @since 2.0 */
         public ParameterException(CommandLine commandLine, String msg, Exception ex) {
             super(msg, ex);
             this.commandLine = Assert.notNull(commandLine, "commandLine");
         }
 
         /** Returns the {@code CommandLine} object for the (sub)command whose input could not be parsed.
          * @return the {@code CommandLine} object for the (sub)command where parsing failed.
          * @since 2.0
          */
         public CommandLine getCommandLine() { return commandLine; }
 
         private static ParameterException create(CommandLine cmd, Exception ex, String arg, int i, String[] args) {
             String msg = ex.getClass().getSimpleName() + ": " + ex.getLocalizedMessage()
                     + " while processing argument at or before arg[" + i + "] '" + arg + "' in " + Arrays.toString(args) + ": " + ex.toString();
             return new ParameterException(cmd, msg, ex);
         }
     }
     /**
      * Exception indicating that a required parameter was not specified.
      */
     public static class MissingParameterException extends ParameterException {
         private static final long serialVersionUID = 5075678535706338753L;
         public MissingParameterException(CommandLine commandLine, String msg) {
             super(commandLine, msg);
         }
 
         private static MissingParameterException create(CommandLine cmd, Collection<Field> missing, String separator) {
             if (missing.size() == 1) {
                 return new MissingParameterException(cmd, "Missing required option '"
                         + describe(missing.iterator().next(), separator) + "'");
             }
             List<String> names = new ArrayList<String>(missing.size());
             for (Field field : missing) {
                 names.add(describe(field, separator));
             }
             return new MissingParameterException(cmd, "Missing required options " + names.toString());
         }
         private static String describe(Field field, String separator) {
             String prefix = (field.isAnnotationPresent(Option.class))
                 ? field.getAnnotation(Option.class).names()[0] + separator
                 : "params[" + field.getAnnotation(Parameters.class).index() + "]" + separator;
             return prefix + Help.DefaultParamLabelRenderer.renderParameterName(field);
         }
     }
 
     /**
      * Exception indicating that multiple fields have been annotated with the same Option name.
      */
     public static class DuplicateOptionAnnotationsException extends InitializationException {
         private static final long serialVersionUID = -3355128012575075641L;
         public DuplicateOptionAnnotationsException(String msg) { super(msg); }
 
         private static DuplicateOptionAnnotationsException create(String name, Field field1, Field field2) {
             return new DuplicateOptionAnnotationsException("Option name '" + name + "' is used by both " +
                     field1.getDeclaringClass().getName() + "." + field1.getName() + " and " +
                     field2.getDeclaringClass().getName() + "." + field2.getName());
         }
     }
     /** Exception indicating that there was a gap in the indices of the fields annotated with {@link Parameters}. */
     public static class ParameterIndexGapException extends InitializationException {
         private static final long serialVersionUID = -1520981133257618319L;
         public ParameterIndexGapException(String msg) { super(msg); }
     }
     /** Exception indicating that a command line argument could not be mapped to any of the fields annotated with
      * {@link Option} or {@link Parameters}. */
     public static class UnmatchedArgumentException extends ParameterException {
         private static final long serialVersionUID = -8700426380701452440L;
         public UnmatchedArgumentException(CommandLine commandLine, String msg) { super(commandLine, msg); }
         public UnmatchedArgumentException(CommandLine commandLine, Stack<String> args) { this(commandLine, new ArrayList<String>(reverse(args))); }
         public UnmatchedArgumentException(CommandLine commandLine, List<String> args) { this(commandLine, "Unmatched argument" + (args.size() == 1 ? " " : "s ") + args); }
     }
     /** Exception indicating that more values were specified for an option or parameter than its {@link Option#arity() arity} allows. */
     public static class MaxValuesforFieldExceededException extends ParameterException {
         private static final long serialVersionUID = 6536145439570100641L;
         public MaxValuesforFieldExceededException(CommandLine commandLine, String msg) { super(commandLine, msg); }
     }
     /** Exception indicating that an option for a single-value option field has been specified multiple times on the command line. */
     public static class OverwrittenOptionException extends ParameterException {
         private static final long serialVersionUID = 1338029208271055776L;
         public OverwrittenOptionException(CommandLine commandLine, String msg) { super(commandLine, msg); }
     }
     /**
      * Exception indicating that an annotated field had a type for which no {@link ITypeConverter} was
      * {@linkplain #registerConverter(Class, ITypeConverter) registered}.
      */
     public static class MissingTypeConverterException extends ParameterException {
         private static final long serialVersionUID = -6050931703233083760L;
         public MissingTypeConverterException(CommandLine commandLine, String msg) { super(commandLine, msg); }
     }
 }