### 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
private volatile URL registeredConsumerUrl;
    /**
     * override rules
     * Priority: override>-D>consumer>provider
     * Rule one: for a certain provider <ip:port,timeout=100>
     * Rule two: for all providers <* ,timeout=5000>
     */
    private volatile List<Configurator> configurators; 
    
    private volatile Map<String, Invoker<T>> urlInvokerMap; 
    private volatile List<Invoker<T>> invokers;
    
    private volatile Set<URL> cachedInvokerUrls; 
    private static final ConsumerConfigurationListener CONSUMER_CONFIGURATION_LISTENER = new ConsumerConfigurationListener();
    private ReferenceConfigurationListener serviceConfigurationListener;
    public RegistryDirectory(Class<T> serviceType, URL url) {
        super(url);
        if (serviceType == null) {
            throw new IllegalArgumentException("service type is null.");
        }
        shouldRegister = !ANY_VALUE.equals(url.getServiceInterface()) && url.getParameter(REGISTER_KEY, true);
        shouldSimplified = !url.getParameter(SIMPLIFIED_KEY, false);
        if (url.getServiceKey() == null || url.getServiceKey().length() == 0) {
            throw new IllegalArgumentException("registry serviceKey is null.");
        }
        this.serviceType = serviceType;
        this.serviceKey = url.getServiceKey();
        this.queryMap = StringUtils.parseQueryString(url.getParameterAndDecoded(REFER_KEY));
        this.overrideDirectoryUrl = this.directoryUrl = turnRegistryUrlToConsumerUrl(url);
        String group = directoryUrl.getParameter(GROUP_KEY, "");