<!-- If you need to report a security issue please visit https://github.com/apache/dubbo/security/policy -->

- [ ] I have searched the [issues](https://github.com/apache/dubbo/issues) of this repository and believe that this is not a duplicate.

### Environment

* Dubbo version: 3.1.1
* Operating System version: macosx
* Java version: 17

### Steps to reproduce this issue
provider:
```
    <dubbo:protocol name="dubbo" serialization="fastjson2" port="20880"></dubbo:protocol>
    <dubbo:service protocol="dubbo" serialization="fastjson2" version="${dubbo.version:3.1.1}" loadbalance="roundrobin" interface="cn.app.service.TestService" timeout="50" registry="dubboRegistry"
                   ref="testService"/>
```
consumer:
The serialization method remains the same as hesian2
![image](https://user-images.githubusercontent.com/19943636/197732272-91b6260a-b23c-4e35-9ac1-980ce8bf75bd.png)
![image](https://user-images.githubusercontent.com/19943636/197732300-eb5fccec-0de0-4211-b240-a0fbd008c1ad.png)

Self-declared dubbo interfaces are normal
![image](https://user-images.githubusercontent.com/19943636/197733004-42fa2710-3ba3-4969-a302-b1706938c9e6.png)


Pls. provide [GitHub address] to reproduce this issue.

### Expected Behavior

<!-- What do you expect from the above steps？-->

### Actual Behavior

<!-- What actually happens? -->

If there is an exception, please attach the exception trace:

```
Just put your stack trace here!
```

for (Map.Entry<String, List<String>> entry : list.entrySet()) {
            result.put(entry.getKey(), split(entry.getValue(), separator));
        }
        return result;
    }
    public static Map<String, List<String>> joinAll(Map<String, Map<String, String>> map, String separator) {
        if (map == null) {
            return null;
        }
        Map<String, List<String>> result = new HashMap<>();
        for (Map.Entry<String, Map<String, String>> entry : map.entrySet()) {
            result.put(entry.getKey(), join(entry.getValue(), separator));
        }
        return result;
    }
    public static Map<String, String> split(List<String> list, String separator) {
        if (list == null) {
            return null;
        }
        Map<String, String> map = new HashMap<>();
        if (list.isEmpty()) {
            return map;
        }
        for (String item : list) {
            int index = item.indexOf(separator);
            if (index == -1) {
                map.put(item, "");
            } else {
                map.put(item.substring(0, index), item.substring(index + 1));
            }