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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
import org.apache.dubbo.common.logger.LoggerFactory;
import org.apache.dubbo.common.url.component.ServiceConfigURL;
import org.apache.dubbo.common.utils.ArrayUtils;
import org.apache.dubbo.common.utils.CollectionUtils;
import org.apache.dubbo.common.utils.ConfigUtils;
import org.apache.dubbo.common.utils.NetUtils;
import org.apache.dubbo.common.utils.StringUtils;
import org.apache.dubbo.common.utils.UrlUtils;
import org.apache.dubbo.config.annotation.Reference;
import org.apache.dubbo.config.support.Parameter;
import org.apache.dubbo.config.utils.ConfigValidationUtils;
import org.apache.dubbo.metadata.ServiceNameMapping;
import org.apache.dubbo.registry.client.metadata.MetadataUtils;
import org.apache.dubbo.rpc.Invoker;
import org.apache.dubbo.rpc.Protocol;
import org.apache.dubbo.rpc.ProxyFactory;
import org.apache.dubbo.rpc.cluster.Cluster;
import org.apache.dubbo.rpc.cluster.directory.StaticDirectory;
import org.apache.dubbo.rpc.cluster.support.ClusterUtils;
import org.apache.dubbo.rpc.cluster.support.registry.ZoneAwareCluster;
import org.apache.dubbo.rpc.model.AsyncMethodInfo;
import org.apache.dubbo.rpc.model.ConsumerModel;
import org.apache.dubbo.rpc.model.ModuleModel;
import org.apache.dubbo.rpc.model.ModuleServiceRepository;
import org.apache.dubbo.rpc.model.ScopeModel;
import org.apache.dubbo.rpc.model.ServiceDescriptor;
import org.apache.dubbo.rpc.protocol.injvm.InjvmProtocol;
import org.apache.dubbo.rpc.service.GenericService;
import org.apache.dubbo.rpc.stub.StubSuppliers;
import org.apache.dubbo.rpc.support.ProtocolUtils;