code: private void validateArgumentValues()  {
          namedArgumentDefinitions = validatePluginArgumentValues(); // trim the list of plugin-derived argument definitions before validation
          for (final NamedArgumentDefinition argumentDefinition : namedArgumentDefinitions) {
              argumentDefinition.validateValues(this);
          }
          if (positionalArgumentDefinition != null) {
              positionalArgumentDefinition.validateValues(this);
          }
      }
docs: After command line has been parsed, make sure that all required arguments have values, and that
  lists with minimum # of elements have sufficient values.
  
  @throws CommandLineException if arguments requirements are not satisfied.