- [*] I have searched the [issues](https://github.com/apache/dubbo/issues) of this repository and believe that this is not a duplicate.
- [*] I have checked the [FAQ](https://github.com/apache/dubbo/blob/master/FAQ.md) of this repository and believe that this is not a duplicate.

### Environment

* Dubbo version: 3.0.2.1
* Operating System version: Ubuntu20
* Java version: 1.8

### Steps to reproduce this issue

1.  telnet localhost 22222
2. dubbo>ls service


Pls. provide [GitHub address] to reproduce this issue.

### Expected Result
list services

### Actual Result

```
ls service :fail to execute commandContext by org.apache.dubbo.registry.client.ServiceDiscoveryRegistry cannot be cast to org.apache.dubbo.registry.support.AbstractRegistry
```

*     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.dubbo.registry.client;
import org.apache.dubbo.common.URL;
import org.apache.dubbo.common.extension.ExtensionLoader;
import org.apache.dubbo.common.logger.Logger;
import org.apache.dubbo.common.logger.LoggerFactory;
import org.apache.dubbo.common.utils.CollectionUtils;
import org.apache.dubbo.metadata.MappingChangedEvent;
import org.apache.dubbo.metadata.MappingListener;
import org.apache.dubbo.metadata.ServiceNameMapping;
import org.apache.dubbo.metadata.WritableMetadataService;
import org.apache.dubbo.registry.NotifyListener;
import org.apache.dubbo.registry.Registry;
import org.apache.dubbo.registry.client.event.ServiceInstancesChangedEvent;
import org.apache.dubbo.registry.client.event.listener.ServiceInstancesChangedListener;
import org.apache.dubbo.registry.client.metadata.SubscribedURLsSynthesizer;
import org.apache.dubbo.registry.support.RegistryManager;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Objects;