}

  final void clearSeenExceptions() {
    seenExceptionsField = null;
  }

  @VisibleForTesting
  static String atomicHelperTypeForTest() {
    return ATOMIC_HELPER.atomicHelperTypeForTest();
  }

  private abstract static class AtomicHelper {
    /** Performs an atomic compare-and-set of {@link AggregateFutureState#seenExceptionsField}. */

  // blocking. This value is what AbstractQueuedSynchronizer uses.
  private static final long SPIN_THRESHOLD_NANOS = 1000L;

  @VisibleForTesting
  static String atomicHelperTypeForTest() {
    return ATOMIC_HELPER.atomicHelperTypeForTest();
  }

  private enum VarHandleAtomicHelperMaker {
    INSTANCE {
      /**
       * Implementation used by non-J2ObjC environments (aside, of course, from those that have

  // blocking. This value is what AbstractQueuedSynchronizer uses.
  private static final long SPIN_THRESHOLD_NANOS = 1000L;

  @VisibleForTesting
  static String atomicHelperTypeForTest() {
    return ATOMIC_HELPER.atomicHelperTypeForTest();
  }

  private abstract static class AtomicHelper {
    /** Non-volatile write of the thread to the {@link Waiter#thread} field. */