code: public void attachNettyPromise(Promise<T> promise) {
      promise.addListener(promiseHandler);
      Promise<T> oldPromise = this.promise;
  
      this.promise = promise;
  
      if (oldPromise != null) {
        oldPromise.removeListener(promiseHandler);
        oldPromise.cancel(true);
      }
    }
docs: Attach Netty Promise
  
  @param promise netty promise to set up response promise with