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 (StringUtils.isEmpty(value)) {
            return defaultValue;
        }
        return value;
    }
    public String[] getParameter(String key, String[] defaultValue) {
        String value = getParameter(key);
        if (StringUtils.isEmpty(value)) {
            return defaultValue;
        }
        return Constants.COMMA_SPLIT_PATTERN.split(value);
    }
    public List<String> getParameter(String key, List<String> defaultValue) {
        String value = getParameter(key);
        if (value == null || value.length() == 0) {
            return defaultValue;
        }
        String[] strArray = Constants.COMMA_SPLIT_PATTERN.split(value);
        return Arrays.asList(strArray);
    }
    private Map<String, Number> getNumbers() {
        if (numbers == null) { 
            numbers = new ConcurrentHashMap<>();
        }
        return numbers;
    }
    private Map<String, URL> getUrls() {
        if (urls == null) { 
            urls = new ConcurrentHashMap<>();
        }