Flutter @freezed Could not generate `toJson` code error

Question

After defining some response data structure i'm trying to build @freezed class, but i get this error:

Could not generate `toJson` code for `medias` because of type `Media`.

after some of research about this problem i can't found how can i resolve this error:

import 'package:freezed_annotation/freezed_annotation.dart';
import 'package:xxxx/screens/search_page/data/media.dart';

part 'account.g.dart';
part 'account.freezed.dart';

@freezed
class Account with _$Account{
  const factory Account({
  //...
  required List<Media>medias,
  //...
})=_Account;

  factory Account.fromJson(Map<String, dynamic> json) =>
      _$AccountFromJson(json);
}


@freezed
class Media with _$Media{
  const factory Media(
      {
        required String shortCode,
        required int createdTime,
        //...
  })=_Media;

  factory Media.fromJson(Map<String, dynamic> json) =>
      _$MediaFromJson(json);
}