请有人帮助我了解此配置中的问题所在：版本：

• 软件框架。集成：spring-集成-mqtt：5.5.2
• 引导程序：Spring引导启动程序：2.5.3
• 请访问：www.eclipse.paho.com

@Configuration
public class MqttConfig {
    @Bean
    public MqttPahoClientFactory mqttClientFactory() {
       DefaultMqttPahoClientFactory factory = new DefaultMqttPahoClientFactory();
       MqttConnectOptions options = new MqttConnectOptions();
       options.setServerURIs(new String[] { "tcp://localhost:1883" });
       return factory;
    }

    @Bean
    public MqttPahoMessageDrivenChannelAdapter inboundAdapter(MqttPahoClientFactory clientFactory) {
        return new MqttPahoMessageDrivenChannelAdapter("MyApp", clientFactory, "ReplyTopic");
    }

    @Bean
    IntegrationFlow inboundFlow(MqttPahoMessageDrivenChannelAdapter inboundAdapter) {
        return IntegrationFlows.from(inboundAdapter)
                               .bridge()
                               .channel("replyChannel")
                               .get();
    }

    @Bean
    public MessageChannel replyChannel() {       
        return MessageChannels.publishSubscribe().get();;
    }

   @Bean
   public MqttPahoMessageHandler outboundAdapter(MqttPahoClientFactory clientFactory) {
        return new MqttPahoMessageHandler("MyApp", clientFactory);
   }

   @Bean
   public IntegrationFlow outboundFlow(MqttPahoMessageHandler outboundAdapter) {
        return IntegrationFlows.from("requestChannel")
                               .handle(outboundAdapter).get()
   }

   @MessagingGateway
   public interface MyGateway {
        @Gateway(requestChannel = "requestChannel", replyChannel = "replyChannel")
        String send(String request, @Header(MqttHeaders.TOPIC) String requestTopic);
   }
}

客户代码

@RestController
public class MyController {
    @Autowired
    private MyGateway myGateway;

    @GetMapping("/sendRequest")
    public String sendRequest() {
       var response = myGateway.send("Hello", "MyTopic");
       return response;
    }
}

用法：

curl http://localhost:8080/sendRequest

来自mqtt代理的手动响应（HiveMQ）

docker exec -it hivemq mqtt pub -t ReplyTopic -m "World" --debug
CLIENT mqttClient-MQTT_5_0-9ecded84-8416-4baa-a8f3-d593c692bc65: acknowledged PUBLISH: 'World' for PUBLISH to Topic:  ReplyTopic

但是我不知道为什么我在Spring应用程序输出中会有这样的消息

2022-10-25 18:04:33.171 ERROR 17069 --- [T Call: MyApp] .m.i.MqttPahoMessageDrivenChannelAdapter : Unhandled exception for GenericMessage [payload=World, headers={mqtt_receivedRetained=false, mqtt_id=0, mqtt_duplicate=false, id=9dbd5e14-66ed-5dc8-6cea-6d04ef19c6cc, mqtt_receivedTopic=ReplyTopic, mqtt_receivedQos=0, timestamp=1666713873170}]

org.springframework.messaging.MessageHandlingException: error occurred in message handler [org.springframework.integration.handler.BridgeHandler@6f63903c]; nested exception is org.springframework.messaging.core.DestinationResolutionException: no output-channel or replyChannel header available

有人能解释一下为什么我有这个吗？

no output-channel or replyChannel header available