@Override
    public void unSubscribe(ConsumerConfig config) {
        UnSubscribeServiceRequest unsubscribeRequest = buildUnSubscribeServiceRequest(config);
        client.unSubscribeService(unsubscribeRequest);
    }
can be extended

@param appName
@return
registry/registry-mesh/src/main/java/com/alipay/sofa/rpc/registry/mesh/MeshRegistry.java