code: @Override
      protected void doHandle(CommandContext ctx) throws CommandLineException {
          final List<String> names = ctx.getParsedCommandLine().getOtherProperties();
          if(names.isEmpty()) {
              throw new CommandFormatException("Variable name is missing");
          }
  
          for (String name : names) {
              if (name.charAt(0) == '$') {
                  name = name.substring(1);
                  if (name.isEmpty()) {
                      throw new CommandFormatException("Variable name is missing after '$'");
                  }
              }
              ctx.setVariable(name, null);
          }
      }
docs: /* (non-Javadoc)
  @see org.jboss.as.cli.handlers.CommandHandlerWithHelp#handle(org.jboss.as.cli.CommandContext, java.lang.String)