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 (value == null || value.length() == 0) {
            return this;
        }
        return addParameter(key, String.valueOf(value));
    }
    public URL addParameter(String key, String value) {
        if (StringUtils.isEmpty(key)
                || StringUtils.isEmpty(value)) {
            return this;
        }
        
        if (value.equals(getParameters().get(key))) { 
            return this;
        }
        Map<String, String> map = new HashMap<>(getParameters());
        map.put(key, value);
        return new URL(protocol, username, password, host, port, path, map);
    }
    public URL addParameterIfAbsent(String key, String value) {
        if (StringUtils.isEmpty(key)
                || StringUtils.isEmpty(value)) {
            return this;
        }
        if (hasParameter(key)) {
            return this;
        }
        Map<String, String> map = new HashMap<>(getParameters());
        map.put(key, value);
        return new URL(protocol, username, password, host, port, path, map);
    }