### Environment

* Dubbo version: 2.7.3
* Operating System version: CentOS7
* Java version: 1.8

### Steps to reproduce this issue

1. Set two protocal, with different "register" attribute

```xml
<dubbo:protocol name="dubbo" port="8751" register="true"  />
<dubbo:protocol name="hessian" port="8752" register="false" />
```

2. use the zookeeper registry center

```xml
<dubbo:registry address="..." file="./.dubbo_cache" />
```

3. start the server and view the provider in zkCli


### Expected Result
only the dubbo is registed

### Actual Result
the dubbo and hession protocol are registed

private transient volatile boolean exported;
    /**
     * The flag whether a service has unexported ,if the method unexported is invoked, the value is true
     */
    private transient volatile boolean unexported;
    /**
     * whether it is a GenericService
     */
    private volatile String generic;
    public ServiceConfig() {
    }
    public ServiceConfig(Service service) {
        appendAnnotation(Service.class, service);
        setMethods(MethodConfig.constructMethodConfig(service.methods()));
    }
    @Deprecated
    private static List<ProtocolConfig> convertProviderToProtocol(List<ProviderConfig> providers) {
        if (CollectionUtils.isEmpty(providers)) {
            return null;
        }
        List<ProtocolConfig> protocols = new ArrayList<ProtocolConfig>(providers.size());
        for (ProviderConfig provider : providers) {
            protocols.add(convertProviderToProtocol(provider));
        }
        return protocols;
    }
    @Deprecated
    private static List<ProviderConfig> convertProtocolToProvider(List<ProtocolConfig> protocols) {
        if (CollectionUtils.isEmpty(protocols)) {
            return null;