clientv3/logger.go
func SetLogger(l grpclog.LoggerV2) {
	lgMu.Lock()
	lg = logutil.NewLogger(l)
	// override grpclog so that any changes happen with locking
	grpclog.SetLoggerV2(lg)
	lgMu.Unlock()
}
func SetLogger(l grpclog.LoggerV2) {
	lgMu.Lock()
	lg = logutil.NewLogger(l)
	// override grpclog so that any changes happen with locking
	grpclog.SetLoggerV2(lg)
	lgMu.Unlock()
}
// SetLogger sets client-side Logger.