### 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" />`
```

public void setLogger(String logger) {
        this.logger = logger;
        LoggerFactory.setLoggerAdapter(logger);
    }
    public Boolean isDefault() {
        return isDefault;
    }
    public void setDefault(Boolean isDefault) {
        this.isDefault = isDefault;
    }
    @Parameter(key = DUMP_DIRECTORY)
    public String getDumpDirectory() {
        return dumpDirectory;
    }
    public void setDumpDirectory(String dumpDirectory) {
        this.dumpDirectory = dumpDirectory;
    }
    @Parameter(key = QOS_ENABLE)
    public Boolean getQosEnable() {
        return qosEnable;
    }
    public void setQosEnable(Boolean qosEnable) {
        this.qosEnable = qosEnable;
    }
    @Parameter(key = QOS_HOST)
    public String getQosHost() {
        return qosHost;
    }
    public void setQosHost(String qosHost) {
        this.qosHost = qosHost;