1. non-simplify mode:
```
dubbo://120.0.0.1:20880/org.apache.dubbo.demo.DemoService?key=value
```
the store path of ZK will be: `/dubbo/porg.apache.dubbo.demo.DemoService/url`

2. simplify mode:
```
dubbo://120.0.0.1:20880/org.apache.dubbo.demo.DemoService?key=value
```
the store path of ZK will be: `/dubbo/porg.apache.dubbo.demo.DemoService/url`

3. simplify mode with path specified:
```
dubbo://120.0.0.1:20880/path-value?key=value
```
the store path of ZK will be: `/dubbo/path-value/url`
if (Constants.PROTOCOL_KEY.equals(key)) {
            return protocol;
        }
        if (Constants.USERNAME_KEY.equals(key)) {
            return username;
        }
        if (Constants.PASSWORD_KEY.equals(key)) {
            return password;
        }
        if (Constants.HOST_KEY.equals(key)) {
            return host;
        }
        if (Constants.PORT_KEY.equals(key)) {
            return String.valueOf(port);
        }
        if (Constants.PATH_KEY.equals(key)) {
            return path;
        }
        return getParameter(key);
    }
    public Map<String, String> toMap() {
        Map<String, String> map = new HashMap<>(parameters);
        if (protocol != null) {
            map.put(Constants.PROTOCOL_KEY, protocol);
        }
        if (username != null) {
            map.put(Constants.USERNAME_KEY, username);
        }
        if (password != null) {
            map.put(Constants.USERNAME_KEY, password);