Why can't I get the method‘s real parameter name when i use apm-agent？

Why can't I get the method‘s real parameter name by reflect？
i can get the method‘s real parameter name When the program first started，but i can‘t get the method's real parameter name after printing this log.

```
2023-07-14 13:58:27,588 [http-nio-8081-exec-4] INFO co.elastic.apm.agent.servlet.ServletVersionInstrumentation - Servlet container info = Apache Tomcat/9.0.60

2023-07-14 13:58:27,710 [Attach Listener] INFO co.elastic.apm.agent.impl.ElasticApmTracer - Tracer switched to RUNNING state
```

**my code like this**
```
@GetMapping("/test01")
public String test01() throws NoSuchMethodException {
Method testMethod = HelloController.class.getDeclaredMethod("test", int.class);
for (Parameter parameter : testMethod.getParameters()) {
System.out.println("param name is" + parameter.getName());
}
return "ok";
}

private static void test(int num) {

}
```

**and log info like this**
```
param name isnum

2023-07-14 13:58:27,588 [http-nio-8081-exec-4] INFO co.elastic.apm.agent.servlet.ServletVersionInstrumentation - Servlet container info = Apache Tomcat/9.0.60

2023-07-14 13:58:27,710 [Attach Listener] INFO co.elastic.apm.agent.impl.ElasticApmTracer - Tracer switched to RUNNING state

param name isarg0
```

**first result is “param name isnum” but the second result is “param name isarg0”，the expected result is “param name isnum”，how can i fix it？**

**my runtime environment is jdk8 and apm-agent-attach 1.39.0**