public synchronized void destroyAllService() {
        for (String serviceKey : servicesCache.keySet()) {
            if (serviceKey == null) {
                continue;
            }
            ServiceHolder h = servicesCache.remove(serviceKey);
            if (h != null) {
                h.shutdown();
            }
        }
    }
check is service empty

@return whether is empty
inlong-tubemq/tubemq-core/src/main/java/org/apache/inlong/tubemq/corerpc/RpcServiceFactory.java