### 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" />`
```

private static final long serialVersionUID = 5508512956753757169L;
    /**
     * Application name
     */
    private String name;
    /**
     * The application version
     */
    private String version;
    /**
     * Application owner
     */
    private String owner;
    /**
     * Application's organization (BU)
     */
    private String organization;
    /**
     * Architecture layer
     */
    private String architecture;
    /**
     * Environment, e.g. dev, test or production
     */
    private String environment;
    /**
     * Java compiler
     */
    private String compiler;
    /**