Unable to create call adapter for class example.Simple

In case of Kotlin and coroutines this situation happened when I forgot to mark api service function as suspend when I call this function from CoroutineScope(Dispatchers.IO).launch{}:

Usage:

    val apiService = RetrofitFactory.makeRetrofitService()

    CoroutineScope(Dispatchers.IO).launch {

        val response = apiService.myGetRequest()

        // process response...

    }

ApiService.kt

interface ApiService {

       @GET("/my-get-request")
       suspend fun myGetRequest(): Response<String>
}