dkelkhoff@mac:> top middle1 bottom1b -v
In bottom1b.call.  verbose: true

dkelkhoff@mac:> top middle1 bottom1b -v
In top.call
Usage: top [-hV] [COMMAND]
  -h, --help      Show this help message and exit.
  -V, --version   Print version information and exit.
Commands:
  middle1
  middle2

import java.util.concurrent.Callable;
import picocli.CommandLine;
import picocli.CommandLine.Command;


/*******************************************************************************
 ** Hierarchy of sub-commands looks like this:
 **
 ** top
 **   middle1
 **      bottom1a
 **      bottom1b
 **   middle2
 **      bottom2a
 **      bottom2b
 **
 *******************************************************************************/
@Command(name = "top", subcommands = { NestingTop.Middle1.class, NestingTop.Middle2.class }, mixinStandardHelpOptions = true, version = "0")
public class NestingTop implements Callable<Void>
{

   public static void main(String[] args)
   {
      new CommandLine(new NestingTop()).execute(args);
   }



   public Void call()
   {
      System.out.println("In top.call");
      new CommandLine(this).usage(System.out);
      return (null);
   }



   @Command(name = "middle1", subcommands = { Bottom1A.class, Bottom1B.class })
   public static class Middle1 implements Callable<Void>
   {
      public Void call()
      {
         System.out.println("In middle1.call");
         new CommandLine(this).usage(System.out);
         return (null);
      }
   }



   @Command(name = "middle2", subcommands = { Bottom2A.class, Bottom2B.class })
   public static class Middle2 implements Callable<Void>
   {
      public Void call()
      {
         System.out.println("In middle2.call");
         new CommandLine(this).usage(System.out);
         return (null);
      }
   }



   @Command(name = "bottom1a", subcommands = {})
   public static class Bottom1A implements Callable<Void>
   {
      public Void call()
      {
         System.out.println("In bottom1a.call");
         return (null);
      }
   }



   @Command(name = "bottom1b", subcommands = {})
   public static class Bottom1B implements Callable<Void>
   {
      @CommandLine.Option(names = { "-v", "--verbose" })
      private boolean verbose;



      public Void call()
      {
         System.out.println("In bottom1b.call.  verbose: "   verbose);
         return (null);
      }
   }



   @Command(name = "bottom2a", subcommands = {})
   public static class Bottom2A implements Callable<Void>
   {
      public Void call()
      {
         System.out.println("In bottom2a.call");
         return (null);
      }
   }



   @Command(name = "bottom2b", subcommands = {})
   public static class Bottom2B implements Callable<Void>
   {
      public Void call()
      {
         System.out.println("In bottom2b.call");
         return (null);
      }
   }

}