code: public static void onPushPromiseRead(Http2PushPromise http2PushPromise, Http2ClientChannel http2ClientChannel,
                                           OutboundMsgHolder outboundMsgHolder) {
          int streamId = http2PushPromise.getStreamId();
          int promisedStreamId = http2PushPromise.getPromisedStreamId();
  
          if (LOG.isDebugEnabled()) {
              LOG.debug("Received a push promise on channel: {} over stream id: {}, promisedStreamId: {}",
                      http2ClientChannel, streamId, promisedStreamId);
          }
  
          if (outboundMsgHolder == null) {
              LOG.warn("Push promise received in channel: {} over invalid stream id : {}", http2ClientChannel, streamId);
              return;
          }
          http2ClientChannel.putPromisedMessage(promisedStreamId, outboundMsgHolder);
          http2PushPromise.setOutboundMsgHolder(outboundMsgHolder);
          outboundMsgHolder.addPromise(http2PushPromise);
      }
docs: Adds a push promise message.
  
  @param http2PushPromise   the HTTP2 push promise
  @param http2ClientChannel the client channel related to the handler
  @param outboundMsgHolder  the outbound message holder