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

### Environment

* Dubbo version: xxx
* Operating System version: xxx
* Java version: xxx

### Steps to reproduce this issue

1. xxx
2. xxx
3. xxx

Pls. provide [GitHub address] to reproduce this issue.

### Expected Result

What do you expected from the above steps？

### Actual Result

What actually happens?

If there is an exception, please attach the exception trace:

```
Just put your stack trace here!
```

package org.apache.dubbo.registry.nacos;
import org.apache.dubbo.common.URL;
import org.apache.dubbo.common.URLBuilder;
import org.apache.dubbo.common.logger.Logger;
import org.apache.dubbo.common.logger.LoggerFactory;
import org.apache.dubbo.common.url.component.DubboServiceAddressURL;
import org.apache.dubbo.common.url.component.ServiceConfigURL;
import org.apache.dubbo.common.utils.StringUtils;
import org.apache.dubbo.common.utils.UrlUtils;
import org.apache.dubbo.registry.NotifyListener;
import org.apache.dubbo.registry.Registry;
import org.apache.dubbo.registry.RegistryNotifier;
import org.apache.dubbo.registry.nacos.util.NacosInstanceManageUtil;
import org.apache.dubbo.registry.support.FailbackRegistry;
import com.alibaba.nacos.api.common.Constants;
import com.alibaba.nacos.api.exception.NacosException;
import com.alibaba.nacos.api.naming.listener.Event;
import com.alibaba.nacos.api.naming.listener.EventListener;
import com.alibaba.nacos.api.naming.listener.NamingEvent;
import com.alibaba.nacos.api.naming.pojo.Instance;
import com.alibaba.nacos.api.naming.pojo.ListView;
import com.google.common.collect.Lists;
import org.apache.dubbo.rpc.RpcException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashMap;
import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.List;