golang + grpc：在GrpcServer上注册服务

I'm working with this example for building a go lang grpc server.

But it seems that I'm missing something - In the example there is a phase of registering a service to the grpc-server but my protoc output has no registration method exported:

s := grpc.NewServer()
pb.RegisterGreeterServer(s, &server{})

Was there a change in the compilation of protobuf3 files?

Am I'm compiling it in the wrong way?

protoc --go_output=. *.proto

And how can I make the service work for the server, It is currently not:

func main() {
    lis, err := net.Listen("tcp", port)
    if err != nil {
        log.Fatalf("failed to listen: %v", err)
    }
    s := grpc.NewServer()
    //register should go here?!
    reflection.Register(s)
    if err := s.Serve(lis); err != nil {
        log.Fatalf("failed to server: %v", err)
    }
}