code: @Override
      public Evaluator getAttributeEvaluator(String name, String mode, String value) {
          return new GroupMembershipEvaluator(mode, name);
      }
docs: Returns an instance of an evaluator specific to this factory and the passed in values. Name
  should be a well known group name. Case is important. The mode should be "memberOf" for now.
  Other modes may be added in the future like, "deepMemberOf".