code: func ReplaceGrpcLogger(logger *zap.Logger) {
  	zgl := &zapGrpcLogger{logger.With(SystemField, zap.Bool("grpc_log", true))}
  	grpclog.SetLogger(zgl)
  }
docs: // ReplaceGrpcLogger sets the given zap.Logger as a gRPC-level logger.
  // This should be called *before* any other initialization, preferably from init() functions.