client.responsePipeline.intercept(HttpResponsePipeline.Transform) { (info, body) ->
    val response = if (context.response.status == HttpStatusCode.OK) {
            //transform to success response
            SuccessResponse(body)
        } else {
           //read error response body?    
        }
    proceedWith(HttpResponseContainer(info, response))
}

val response: MyCustomResponse = client.get("some url")

{
  "name": "NAME",
  "message": "MESSAGE"
}

{
  "error": "ERROR",
  "message": "MESSAGE"
}