}

    @Override
    void putNext(Waiter waiter, @CheckForNull Waiter newValue) {
      UNSAFE.putObject(waiter, WAITER_NEXT_OFFSET, newValue);
    }

    /** Performs a CAS operation on the {@link #waiters} field. */
    @Override
    boolean casWaiters(
        AbstractFuture<?> future, @CheckForNull Waiter expect, @CheckForNull Waiter update) {