code: private static Tuple3<Set<Object>, Set<PathSpec>, Boolean> reduceRequests(final Tuple3<Set<Object>, Set<PathSpec>, Boolean> state,
        final Request<?> rq) {
      return reduceContainsBatch(reduceIds(reduceFields(state, rq), rq), rq);
    }
docs: Tuple3: (keys, fields, contains-batch-get)