### Environment

* Dubbo version: 2.7.5
* Operating System version: win10 or centos7
* Java version: 1.8.0
* Zookeeper version: 3.5.6

### Steps to reproduce this issue
My previous dubbo service version was 2.7.3. Today, I upgraded to 2.7.5. I found that the metadata can't be displayed all the time. The dubbo service registry in zookeeper, but zookeeper not /dubbo/metadata node path view.  If I switch back to 2.7.3 and 2.7.4.1, it can be displayed. Are there any bugs? I need help~~

xml-config:
`<dubbo:metadata-report address="zookeeper://192.168.11.100:2181?backup=192.168.11.105:2181" />`
```

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.common.utils.StringUtils;
import org.apache.dubbo.config.support.Parameter;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import static org.apache.dubbo.common.constants.CommonConstants.APPLICATION_KEY;
import static org.apache.dubbo.common.constants.CommonConstants.DUMP_DIRECTORY;
import static org.apache.dubbo.common.constants.CommonConstants.HOST_KEY;
import static org.apache.dubbo.common.constants.CommonConstants.SHUTDOWN_WAIT_KEY;
import static org.apache.dubbo.common.constants.QosConstants.ACCEPT_FOREIGN_IP;
import static org.apache.dubbo.common.constants.QosConstants.QOS_ENABLE;
import static org.apache.dubbo.common.constants.QosConstants.QOS_HOST;
import static org.apache.dubbo.common.constants.QosConstants.QOS_PORT;
import static org.apache.dubbo.config.Constants.DEVELOPMENT_ENVIRONMENT;
import static org.apache.dubbo.config.Constants.PRODUCTION_ENVIRONMENT;
import static org.apache.dubbo.config.Constants.TEST_ENVIRONMENT;
/**
 * The application info
 *
 * @export
 */
public class ApplicationConfig extends AbstractConfig {
    private static final Logger LOGGER = LoggerFactory.getLogger(ApplicationConfig.class);