[QUESTION] - 针对org.json.JSONObject无法生成对应的契约

### Steps to reproduce (if applicable)

所使用开源软件为org.json:json版本号为20240303

定义一个Controller接口，返回类型为
```
class A {
String data;
JSONObject detail;
}
```

生成契约时报错空指针异常
Caused by: java.lang.IllegalStateException: Generate swagger operation failed, method=TestController:test, cause=Cannot invoke "io.swagger.v3.oas.models.media.Schema.get$ref()" because "result" is null
at org.apache.servicecomb.swagger.generator.core.AbstractSwaggerGenerator.scanMethods(AbstractSwaggerGenerator.java:240)
at org.apache.servicecomb.swagger.generator.core.AbstractSwaggerGenerator.generate(AbstractSwaggerGenerator.java:122)
at org.apache.servicecomb.swagger.generator.SwaggerGenerator.generate(SwaggerGenerator.java:33)
at org.apache.servicecomb.swagger.engine.SwaggerEnvironment.createProducer(SwaggerEnvironment.java:120)
at org.apache.servicecomb.core.provider.producer.ProducerProviderManager.registerSchema(ProducerProviderManager.java:98)
at org.apache.servicecomb.core.provider.producer.ProducerProviderManager.registerProducerMetas(ProducerProviderManager.java:87)
at org.apache.servicecomb.core.provider.producer.ProducerProviderManager.init(ProducerProviderManager.java:73)
at org.apache.servicecomb.core.SCBEngine.doRun(SCBEngine.java:359)

### What have you tried so far?

_No response_

### Additional context

_No response_

Reproduce the failure with org.json:json 20240303 and the controller return type described in the issue, then inspect AbstractSwaggerGenerator.scanMethods at line 240 and the SwaggerGenerator entry point. Determine the expected contract representation for JSONObject and ensure generation completes without the reported null result; add or update a focused regression test if the relevant test location is identified.

Written by the indexing model from the issue text.