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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
*
     * @return reference parameters
     */
    private Map<String, String> appendConfig() {
        Map<String, String> map = new HashMap<>(16);
        map.put(INTERFACE_KEY, interfaceName);
        map.put(SIDE_KEY, CONSUMER_SIDE);
        ReferenceConfigBase.appendRuntimeParameters(map);
        if (!ProtocolUtils.isGeneric(generic)) {
            String revision = Version.getVersion(interfaceClass, version);
            if (StringUtils.isNotEmpty(revision)) {
                map.put(REVISION_KEY, revision);
            }
            String[] methods = methods(interfaceClass);
            if (methods.length == 0) {
                logger.warn(CONFIG_NO_METHOD_FOUND, "", "", "No method found in service interface: " + interfaceClass.getName());
                map.put(METHODS_KEY, ANY_VALUE);
            } else {
                map.put(METHODS_KEY, StringUtils.join(new HashSet<>(Arrays.asList(methods)), COMMA_SEPARATOR));
            }
        }
        AbstractConfig.appendParameters(map, getApplication());
        AbstractConfig.appendParameters(map, getModule());
        AbstractConfig.appendParameters(map, consumer);
        AbstractConfig.appendParameters(map, this);
        appendMetricsCompatible(map);
        String hostToRegistry = ConfigUtils.getSystemProperty(DUBBO_IP_TO_REGISTRY);
        if (StringUtils.isEmpty(hostToRegistry)) {
            hostToRegistry = NetUtils.getLocalHost();
        } else if (isInvalidLocalHost(hostToRegistry)) {