### 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
public Class<T> getInterface() {
        return serviceType;
    }
    @Override
    public List<Invoker<T>> getAllInvokers() {
        return invokers;
    }
    @Override
    public URL getConsumerUrl() {
        return this.overrideDirectoryUrl;
    }
    public URL getRegisteredConsumerUrl() {
        return registeredConsumerUrl;
    }
    public void setRegisteredConsumerUrl(URL url) {
        if (!shouldSimplified) {
            this.registeredConsumerUrl = url.addParameters(CATEGORY_KEY, CONSUMERS_CATEGORY, CHECK_KEY,
                    String.valueOf(false));
        } else {
            this.registeredConsumerUrl = URL.valueOf(url, DEFAULT_REGISTER_CONSUMER_KEYS, null).addParameters(
                    CATEGORY_KEY, CONSUMERS_CATEGORY, CHECK_KEY, String.valueOf(false));
        }
    }
    @Override
    public boolean isAvailable() {
        if (isDestroyed()) {
            return false;
        }
        Map<String, Invoker<T>> localUrlInvokerMap = urlInvokerMap;
        if (localUrlInvokerMap != null && localUrlInvokerMap.size() > 0) {