Update proto package imports to google.golang.org/protobuf/proto

[delgec]

Hello everyone

Why is this dependency not removed?

It's deprecated and we are constantly receiving warnings in the our applications.

github.com/golang/protobuf v1.5.2

[dfawley]

We looked into this migration a year or two ago, but it's a non-trivial amount of work (due to the API changes) for a relatively small benefit (it's been rewritten internally to use the new library already).

[menghanl]

This was discussed in #5110

[dfawley]

...which was a dupe of #3554

I think we should have an issue for this open, but we have no upcoming plans to do anything here.

[gunturaf]

I tried to remove all references to github.com/golang/protobuf, but stuck with the file testv3.pb.go in reflection/grpc_testing_not_regenerate, it's said that we should not regenerate the pb inside that package... I only came up with several possible solutions:

• turn grpc_testing_not_regenerate into sub-module, but with this approach we need to add a replace directive to the root go.mod to enable go mod tidy
• make reflection package pure of testing by moving all test code to the root test directory, but I think this will still cause the root module requires github.com/golang/protobuf

wdyt?

[dfawley]

FWIW I created golang/protobuf#1442 so we can try to get a non-deprecated way of maintaining our existing API.

[chriscasola]

Is there a path forward now that golang/protobuf#1442 has been resolved? I may be able to contribute.