pkg/logutil/zap_grpc.go
func NewGRPCLoggerV2(lcfg zap.Config) (grpclog.LoggerV2, error) {
	lg, err := lcfg.Build(zap.AddCallerSkip(1)) // to annotate caller outside of "logutil"
	if err != nil {
		return nil, err
	}
	return &zapGRPCLogger{lg: lg, sugar: lg.Sugar()}, nil
}
func NewGRPCLoggerV2(lcfg zap.Config) (grpclog.LoggerV2, error) {
	lg, err := lcfg.Build(zap.AddCallerSkip(1)) // to annotate caller outside of "logutil"
	if err != nil {
		return nil, err
	}
	return &zapGRPCLogger{lg: lg, sugar: lg.Sugar()}, nil
}
// NewGRPCLoggerV2 converts "*zap.Logger" to "grpclog.LoggerV2".
// It discards all INFO level logging in gRPC, if debug level
// is not enabled in "*zap.Logger".