当 `onMessage` 要转换的消息类型为 `byte[]` 时，报错：ClassCastException: java.lang.String cannot be cast to [B

https://github.com/apache/rocketmq-spring/blob/b3963f76589a5348370ea990c15e3878806e2710/rocketmq-spring-boot/src/main/java/org/apache/rocketmq/spring/support/DefaultRocketMQListenerContainer.java#L543-L551


我注意到这里当要转换的类型为 `byte[]` 时，会调用`spring-messaging` 的 `ByteArrayMessageConverter` 的 `convertFromInternal`，而这个方法会原样返回 `payload`。而截图的 [`L551` 行](https://github.com/apache/rocketmq-spring/blob/b3963f76589a5348370ea990c15e3878806e2710/rocketmq-spring-boot/src/main/java/org/apache/rocketmq/spring/support/DefaultRocketMQListenerContainer.java#L543-L551)，将 `payload` 设置成了 `str`，导致 `String` 到 `byte[]` 的类型转换异常 `ClassCastException: java.lang.String cannot be cast to [B` 。
```java
org.springframework.messaging.converter.ByteArrayMessageConverter#convertFromInternal

return message.getPayload();
```