java.lang.Class cannot be cast to java.lang.reflect.ParameterizedType using Coroutines Suspend function

I'm trying to setup a mechanism for retrofit in order to fetch data from both local jsons and remote API.

@Provides
@LoginScope
open fun providesLoginService(retrofitAPI: RetrofitAPI) : LoginService {
    return retrofitAPI.createService<LoginService>(LoginService::class.java)
}

For remote API, everything works fine. For local JSONs files I am using a proxy:

 private fun <Service> createServiceDemo(mClass: Class<Service>): Service {
    return Proxy.newProxyInstance(
        mClass.classLoader,
        arrayOf(mClass),
        DemoInvocationHandler(mContext)
    ) as Service
}

fun <Service> createService(mClass: Class<Service>) : Service {

    val service = if (abSession.isDemoMode() == true) {
        createServiceDemo(mClass)
    } else {
        retrofit.create(mClass)
    }

    return service
}

This is the Invocation Handler class where I have the problem:

class DemoInvocationHandler(val context: Context) : InvocationHandler {
@Throws(Throwable::class)
override fun invoke(proxy: Any?, method: Method?, args: Array<out Any>?): Any {

    val returnType = method?.genericReturnType
    
    val parameterizedType = returnType as ParameterizedType
    val _classResponse = TypeToken.get(parameterizedType.actualTypeArguments[0]).type
    val demo = method?.getAnnotation(Demo::class.java)
    return CallFromJSON<Any?>(context, demo?.demoFile ?: "", _classResponse)
}

}

method?.genericReturnType always returns an Object instead of returning the Generic Type.

This is the thrown message: java.lang.Class cannot be cast to java.lang.reflect.ParameterizedType

Once I remove the suspend keyword from loginOld method, the cast is working.

I guess I have a problem with reflection combined with coroutines.

Any help ? Thanks in advance.