code: private static Tuple3<Set<Object>, Set<PathSpec>, Boolean> reduceIds(Tuple3<Set<Object>, Set<PathSpec>, Boolean> state,
        Request<?> request) {
      if (request instanceof GetRequest) {
        GetRequest<?> getRequest = (GetRequest<?>)request;
        state._1().add(getRequest.getObjectId());
        return state;
      } else if (request instanceof BatchRequest) {
        BatchRequest<?> batchRequest = (BatchRequest<?>)request;
        state._1().addAll(batchRequest.getObjectIds());
        return state;
      } else {
        throw unsupportedGetRequestType(request);
      }
    }
docs: Tuple3: (keys, fields, contains-batch-get)