<!-- If you need to report a security issue please visit https://github.com/apache/dubbo/security/policy -->

- [x] I have searched the [issues](https://github.com/apache/dubbo/issues) of this repository and believe that this is not a duplicate.

## Ask your question here
操作步骤如下：
1. k8s环境下，consumer端开启mesh模式
2. consumer端需要调用多个provider
3. provider有应用级注册和接口级注册，并且需要的provider不再同一个namespace下
4. 原有项目存在dubbo2.6与3.1多版本间的相互调用，在开启消费端mesh（dubbo3.1）后，无法调用到2.6的服务提供者

**问题：**

1. 如何实现在一个consumer下，调用多个namespace下的provider，并且provider有应用级注册和接口级注册
2. dubbo3.1消费端在开启mesh后，如何调用版本是2.6的服务提供者
ref = createProxy(referenceParameters);
            serviceMetadata.setTarget(ref);
            serviceMetadata.addAttribute(PROXY_CLASS_REF, ref);
            consumerModel.setDestroyRunner(getDestroyRunner());
            consumerModel.setProxyObject(ref);
            consumerModel.initMethodModels();
            checkInvokerAvailable();
        } catch (Throwable t) {
            try {
                if (invoker != null) {
                    invoker.destroy();
                }
            } catch (Throwable destroy) {
                logger.warn(CONFIG_FAILED_DESTROY_INVOKER, "", "", "Unexpected error occurred when destroy invoker of ReferenceConfig(" + url + ").", t);
            }
            if (consumerModel != null) {
                ModuleServiceRepository repository = getScopeModel().getServiceRepository();
                repository.unregisterConsumer(consumerModel);
            }
            initialized = false;
            invoker = null;
            ref = null;
            consumerModel = null;
            serviceMetadata.setTarget(null);
            serviceMetadata.getAttributeMap().remove(PROXY_CLASS_REF);
            // 
            if (t.getClass() == IllegalStateException.class &&
                t.getMessage().contains("No provider available for the service")) {
                // 
                logger.error(CLUSTER_NO_VALID_PROVIDER, "server crashed", "", "No provider available.", t);