I am working on https://github.com/grpc-ecosystem/grpc-gateway/pull/1228, and would like to regenerate `examples/internal/helloworld/helloworld.pb.gw.go` I ran the commands as per [this](https://github.com/grpc-ecosystem/grpc-gateway/blob/master/CONTRIBUTING.md#i-want-to-regenerate-the-files-after-making-changes), and it renegerated all examples except that one