docs: public static Authorization append(Authorization a, Authorization b) {
          if (a instanceof AclRuleSetSource && b instanceof AclRuleSetSource) {
              return RuleEvaluator.createRuleEvaluator(
                      merge((AclRuleSetSource) a, (AclRuleSetSource) b)
              );
          }
          return new MultiAuthorization(a, b);
      }