toJson() isn't working as expected

[mhmzdev]

I have two freezed model classes as given below:

AuthMeta.dart

@freezed
class AuthMeta with _$AuthMeta {
  const factory AuthMeta({
    required String uid,
    required String fullName,
    required String username,
    required String imageUrl,
    required UserGender gender,
  }) = _AuthMeta;

  factory AuthMeta.fromJson(Map<String, Object?> json) =>
      _$AuthMetaFromJson(json);
}

Comment

@freezed
class Comment with _$Comment {
  const factory Comment({
    required String id,
    required String uid,
    required String comment,
    required AuthMeta authMeta,
    @Default(true) bool visible,
    @Default(false) bool pinned,
    required DateTime createdAt,
  }) = _Comment;

  factory Comment.fromJson(Map<String, Object?> json) =>
      _$CommentFromJson(json);
}

But when I do something like this:

final commentObject = Comment( // filled with values);
commentObject.toJson();

It won't do toJson() to the AuthMeta object inside it.

Work around

For the time being, what I did is in comment.g.dart:

Map<String, dynamic> _$$CommentImplToJson(_$CommentImpl instance) =>
    <String, dynamic>{
      'id': instance.id,
      'uid': instance.uid,
      'comment': instance.comment,
      'authMeta': instance.authMeta.toJson(), // Write thie manually
      'visible': instance.visible,
      'pinned': instance.pinned,
      'createdAt': instance.createdAt.toIso8601String(),
    };

Is there something I'm doing wrong? or is this expected? If it's expected is there any way I can force it to make .toJson() for any nested freezed model.
Or any reference in documentation?

[rrousselGit]

As per the documentation of JSON encoding, you have to enable explicit_to_json in JSON_Serializable

Be it in the build.yaml or using a custom JsonSerializable annotation