### 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
this.multiGroup = group != null && (ANY_VALUE.equals(group) || group.contains(","));
    }
    private URL turnRegistryUrlToConsumerUrl(URL url) {
        return URLBuilder.from(url)
                .setPath(url.getServiceInterface())
                .clearParameters()
                .addParameters(queryMap)
                .removeParameter(MONITOR_KEY)
                .build();
    }
    public void setProtocol(Protocol protocol) {
        this.protocol = protocol;
    }
    public void setRegistry(Registry registry) {
        this.registry = registry;
    }
    public Registry getRegistry() {
        return registry;
    }
    public boolean isShouldRegister() {
        return shouldRegister;
    }
    public void subscribe(URL url) {
        setConsumerUrl(url);
        CONSUMER_CONFIGURATION_LISTENER.addNotifyListener(this);
        serviceConfigurationListener = new ReferenceConfigurationListener(this, url);
        registry.subscribe(url, this);
    }
    public void unSubscribe(URL url) {
        setConsumerUrl(null);