grpc metadata to http header

[RexLyc]

I'm trying to use go-zero as an http api gateway for my other grpc backend services. By using "Grpc-Metadata-xxx", I can write some headers in http request and get them in grpc services.

But when I want to write some metadata in grpc and get these key-values from http headers. I find that the EventHandler in go-zero is empty. So the metadata in grpc resp header is dropped.

I'm not sure whether I'm in the right way to use go-zero as an api-gateway. Or I need to write some code in go-zero to make it possible.