I pulled this commit into the conformance repo to verify that this change is compatible with the official gRPC-Web JS client. In fact, I added some conformance test cases around it (https://github.com/connectrpc/conformance/pull/770) to verify that a gRPC-Web client will correctly accept both forms of "empty" response (for both unary and streams):
1) Headers, no response messages, trailers in the body
2) Trailers-only (where trailers are in HTTP headers)
The only issue with the gRPC-Web JS client was that it doesn't like it when in-body trailers contains a key more than once. It doesn't fail, but later values overwrite earlier ones instead of it merging all of the values. (I went ahead and filed a bug for it: https://github.com/grpc/grpc-web/issues/1399. It's trivial to fix, so I might open a pull request, too.)
I pulled this commit into the conformance repo to verify that this change is compatible with the official gRPC-Web JS client. In fact, I added some conformance test cases around it (https://github.com/connectrpc/conformance/pull/770) to verify that a gRPC-Web client will correctly accept both forms of "empty" response (for both unary and streams): 1) Headers, no response messages, trailers in the body 2) Trailers-only (where trailers are in HTTP headers)
The only issue with the gRPC-Web JS client was that it doesn't like it when in-body trailers contains a key more than once. It doesn't fail, but later values overwrite earlier ones instead of it merging all of the values. (I went ahead and filed a bug for it: https://github.com/grpc/grpc-web/issues/1399. It's trivial to fix, so I might open a pull request, too.)