code: void signalProtocolEstablished(String inboundProtocol) {
          assert !channel.isClientMode() : "Signal protocol should only be made on channel in serverMode";
          this.inboundProtocol = inboundProtocol;
          channel.outboundPipeline().wakeup();
      }
docs: Signals the ProtocolEncoder that the protocol is known. This call will be
  made by the ProtocolDecoder as soon as it knows the inbound protocol.
  
  @param inboundProtocol