code: protected void handlePromise(Promise<T> promise) {
      if (!promise.isSuccess()) {
        this.setException(promise.cause());
      } else {
        this.response = promise.getNow();
        if (handlers != null) {
          for (IsSimplePromiseResponseHandler<T> h : handlers) {
            h.onResponse(this);
          }
        }
      }
    }
docs: Handle the promise
  
  @param promise to handle