map1 ++ ( for ( (k,v) <- map2 ) yield ( k -> ( v + map1.getOrElse(k,0) ) ) )
// First
@Multipart
@POST("retrofit-example/multipartPOSTtest.php")
fun uploadFile(@Part file: MultipartBody.Part): Call<FileResponse>
// Second
@Multipart
@POST("retrofit-example/multipartPOSTtest.php")
fun uploadFile(@Part file: MultipartBody.Part,
@Part("postTest") valForPOST: RequestBody): Call<FileResponse>
Метод ответа: pastebin