code: public WebSocketTransportRegistration setDecoratorFactories(
  			WebSocketHandlerDecoratorFactory... factories) {
  		if (factories != null) {
  			this.decoratorFactories.addAll(Arrays.asList(factories));
  		}
  		return this;
  	}
docs: Configure one or more factories to decorate the handler used to process WebSocket
  messages. This may be useful in some advanced use cases, for example to allow
  Spring Security to forcibly close the WebSocket session when the corresponding HTTP
  session expires.