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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
* Service tag name
     */
    String tag() default "";
    /**
     * Service merger
     */
    String merger() default "";
    /**
     * methods support
     */
    Method[] methods() default {};
    /**
     * The id
     * NOTE: The id attribute is ignored when using @DubboReference on @Bean method
     *
     * @return default value is empty
     * @since 2.7.3
     */
    String id() default "";
    /**
     * @return The service names that the Dubbo interface subscribed
     * @see RegistryConstants#SUBSCRIBED_SERVICE_NAMES_KEY
     * @since 2.7.8
     * @deprecated using {@link DubboReference#providedBy()}
     */
    @Deprecated
    String[] services() default {};
    /**
     * declares which app or service this interface belongs to
     *