dubbo-go: Get weird error message: `pkg.Unmarshal(len(@data):0) = error:get wrong attachments: ` in the server

What happened: Get weird error message: pkg.Unmarshal(len(@data):0) = error:get wrong attachments: <nil> in the server code.

What you expected to happen: Server works as expected.

How to reproduce it (as minimally and precisely as possible):

1. use tengine as http2dubbo proxy, with configuration in the example: https://github.com/alibaba/tengine/tree/master/modules/mod_dubbo
2. write a dubbo server with dubbo-go
3. request with curl http://127.0.0.1:8080/dubbo -i

Anything else we need to know?: The same thing doesn’t happen with the tengine’s Java example. It works as the document states.