return waitFor(combiningCallable, CombiningCallable.class);
    }

    @SuppressWarnings("unchecked") // proxy for a generic class
    <V> AsyncCombiningCallable<V> waitFor(AsyncCombiningCallable<V> asyncCombiningCallable) {
      return waitFor(asyncCombiningCallable, AsyncCombiningCallable.class);
    }

    @SuppressWarnings("unchecked") // proxy for a generic class