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

### Environment

* Dubbo version: 2.7.0
* Operating System version: Windows7
* Java version: jdk8

### Steps to reproduce this issue

1. stop dubbo service
2. dubbo client set checked = true.  do get cudbbo client for times.
3. the size of list field [urls] in ReferenceConfig wil increase

Pls. provide [GitHub address] to reproduce this issue.
(project)[https://github.com/vio-lin/incubator-dubbo/tree/error-situation]  
run java file 
 incubator-dubbo\dubbo-demo\dubbo-demo-xml\dubbo-demo-xml-consumer\src\main\java\org\apache\dubbo\demo\consumer\Application.java
### Expected Result
the [urls] in ReferenceConfig will be updated.

### Actual Result
the avalidable registery urls be add to [urls] in ReferenceConfig

Class serviceInterface = interfaceClass;
        if (interfaceClass == GenericService.class) {
            try {
                serviceInterface = Class.forName(interfaceName);
                methods = serviceInterface.getMethods();
            } catch (ClassNotFoundException e) {
                methods = interfaceClass.getMethods();
            }
        }
        return new ConsumerModel(serviceKey, serviceInterface, ref, methods, attributes);
    }
    @SuppressWarnings({"unchecked", "rawtypes", "deprecation"})
    private T createProxy(Map<String, String> map) {
        if (shouldJvmRefer(map)) {
            URL url = new URL(LOCAL_PROTOCOL, LOCALHOST_VALUE, 0, interfaceClass.getName()).addParameters(map);
            invoker = REF_PROTOCOL.refer(interfaceClass, url);
            if (logger.isInfoEnabled()) {
                logger.info("Using injvm service " + interfaceClass.getName());
            }
        } else {
            if (url != null && url.length() > 0) { // 
                String[] us = SEMICOLON_SPLIT_PATTERN.split(url);
                if (us != null && us.length > 0) {
                    for (String u : us) {
                        URL url = URL.valueOf(u);
                        if (StringUtils.isEmpty(url.getPath())) {
                            url = url.setPath(interfaceName);
                        }
                        if (REGISTRY_PROTOCOL.equals(url.getProtocol())) {
                            urls.add(url.addParameterAndEncoded(REFER_KEY, StringUtils.toQueryString(map)));