### Environment

* Dubbo version: 2.7.6-SNAPSHOT
* Operating System version: Mac
* Java version: 1.8

### Steps to reproduce this issue

run dubbo-samples-simplified-registry-xml 

org.apache.dubbo.samples.simplified.registry.xml.DemoServiceIT
### Expected Result

should pass

### Actual Result

throw exception
import org.apache.dubbo.registry.AddressListener;
import org.apache.dubbo.registry.NotifyListener;
import org.apache.dubbo.registry.Registry;
import org.apache.dubbo.remoting.Constants;
import org.apache.dubbo.rpc.Invocation;
import org.apache.dubbo.rpc.Invoker;
import org.apache.dubbo.rpc.Protocol;
import org.apache.dubbo.rpc.RpcException;
import org.apache.dubbo.rpc.cluster.Cluster;
import org.apache.dubbo.rpc.cluster.Configurator;
import org.apache.dubbo.rpc.cluster.Router;
import org.apache.dubbo.rpc.cluster.RouterChain;
import org.apache.dubbo.rpc.cluster.RouterFactory;
import org.apache.dubbo.rpc.cluster.directory.AbstractDirectory;
import org.apache.dubbo.rpc.cluster.directory.StaticDirectory;
import org.apache.dubbo.rpc.cluster.governance.GovernanceRuleRepository;
import org.apache.dubbo.rpc.cluster.support.ClusterUtils;
import org.apache.dubbo.rpc.model.ApplicationModel;
import org.apache.dubbo.rpc.protocol.InvokerWrapper;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Optional;
import java.util.Set;
import java.util.stream.Collectors;