protected UnSubscribeServiceRequest buildUnSubscribeServiceRequest(ConsumerConfig config) {
        UnSubscribeServiceRequest unsubscribeRequest = new UnSubscribeServiceRequest();
        String key = MeshRegistryHelper.buildMeshKey(config, config.getProtocol());
        unsubscribeRequest.setServiceName(key);
        unsubscribeRequest.setProtocolType(config.getProtocol());
        String group = config.getParameter(SofaRegistryConstants.SOFA_GROUP_KEY);
        if (StringUtils.isNotBlank(group)) {
            unsubscribeRequest.setGroup(group);
        }
        return unsubscribeRequest;
    }
can be extended

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