protoc-gen-go: missing service definition in generated Go files

[r3code]

What version of protobuf and what language are you using?
Version: libprotoc 3.10.1

What did you do?
protoc -I. --go_out=plugins=paths=source_relative,grpc:gen_buggy\go\ *.proto

What did you expect to see?
Generated Go file contains *APIClient and *APIServer functions.
Or error reported of inconsistent or incompatible params.

What did you see instead?
Generated Go file does not contain *APIClient and *APIServer functions.
No errors generated.

Anything else we should know about your project / environment?
This one protoc -I. --go_out=plugins=grpc,paths=source_relative:gen\go *.proto generates go code correct.

Example proto-file:

syntax = "proto3";

package protocgengo.test.bug_source_related;

option go_package = "bug_source_related";

service AuthAPI {   
  rpc Login (LoginQuery) returns (LoginAnswer) {} 
}
             
message LoginQuery {
  string auth_token = 1; // required; 
} 

message LoginAnswer {  
  string error = 1;   
}
        

[r3code]

Relatred #544

[dsnet]

This project is no longer responsible for generating the service bindings as that behavior is moving over to the grpc-go project.