您的问题是因为您将一条消息包装到另一条消息中.

Your problem is because you wrap one message to another.

你的 buildMessageForMultipart(multipartMap); 做了什么?

我确信简单的地图作为有效载荷和那些标头就足够了.

I'm sure the simple map as payload and those header would be enough.

不确定将一条消息包装到另一条消息有什么意义.

Not sure what is the point to wrap one message to another.