class DefaultPromise extends AbstractFuture<V> implements Promise<V> {

    @Override
    public boolean cancel(boolean mayInterruptIfRunning) {
        if (RESULT_UPDATER.compareAndSet(this, null, CANCELLATION_CAUSE_HOLDER)) {
            checkNotifyWaiters();
            notifyListeners();
            return true;
        }
        return false;
    }

    public  DefaultPromise(EventExecutor executor);
    protected  DefaultPromise();

}