Dubbo Version: 3.0.10
注册失败，unexport时，subscribeUrl和registerUrl此时为空，需要判断空处理。 
<img width="944" alt="image" src="https://user-images.githubusercontent.com/12670328/200469537-41a4ccb5-adda-4231-9f71-9af9fec2172d.png">


}
    public RegistryProtocol() {
    }
    @Override
    public void setFrameworkModel(FrameworkModel frameworkModel) {
        this.frameworkModel = frameworkModel;
    }
    public void setProtocol(Protocol protocol) {
        this.protocol = protocol;
    }
    public void setProxyFactory(ProxyFactory proxyFactory) {
        this.proxyFactory = proxyFactory;
    }
    @Override
    public int getDefaultPort() {
        return 9090;
    }
    public Map<URL, NotifyListener> getOverrideListeners() {
        Map<URL, NotifyListener> map = new HashMap<>();
        List<ApplicationModel> applicationModels = frameworkModel.getApplicationModels();
        if (applicationModels.size() == 1) {
            return applicationModels.get(0).getBeanFactory().getBean(ProviderConfigurationListener.class).getOverrideListeners();
        } else {
            for (ApplicationModel applicationModel : applicationModels) {
                map.putAll(applicationModel.getBeanFactory().getBean(ProviderConfigurationListener.class).getOverrideListeners());
            }
        }
        return map;
    }
    private void register(Registry registry, URL registeredProviderUrl) {