code: @Override
      public Future<Void> destroy(final Channel channel, final Promise<Void> promise) {
          channel.close().addListener(new PromiseNotifier<>(promise));
          return promise;
      }
docs: Destroys a channel by closing it.
  
  @param channel the channel to destroy
  @param promise the promise to notify when the channel has been destroyed
  
  @return a future that will be notified when the channel has been destroyed