code: @Override
    public Answer processRequest(Request request) {
      if (logger.isInfoEnabled()) {
        logger.info("Diameter Stack Mux :: processRequest :: Command-Code [" + request.getCommandCode() + "]");
      }
  
      DiameterListener listener = findListener(request);
  
      if (listener != null) {
        return listener.processRequest(request);
      }
      else {
        try {
          Answer answer = request.createAnswer(ResultCode.APPLICATION_UNSUPPORTED);
          //this.stack.getSessionFactory().getNewRawSession().send(answer);
          return answer;
        }
        catch (Exception e) {
          logger.error("Failed to create APPLICATION UNSUPPORTED answer.", e);
        }
      }
      return null;
    }
docs: ===== NetworkReqListener IMPLEMENTATION =====