public synchronized void publishService(Class clazz, Object serviceInstance,
            int listenPort, RpcConfig config) throws Exception {
        publishService(clazz, serviceInstance, listenPort, null, config);
    }
check is service empty

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