seenExceptionsUpdater.compareAndSet(state, expect, update);
    }

    @Override
    int decrementAndGetRemainingCount(AggregateFutureState<?> state) {
      return remainingCountUpdater.decrementAndGet(state);
    }
  }

  private static final class SynchronizedAtomicHelper extends AtomicHelper {
    @Override
    void compareAndSetSeenExceptions(