toJson will not add if we use freezed.

[b14cknc0d3]

Describe the bug toJson will not add if we use freezed. and show this warning

YourModel must provide a `toJson()` method which return a Map.

To Reproduce Steps to reproduce the behavior:

1. create a model with freezed

@freezed
class FoodTagCreateModel with _$FoodTagCreateModel {
  const factory FoodTagCreateModel({
    required String name,
    required String description,
  }) = _FoodTagCreateModel;

  factory FoodTagCreateModel.fromJson(Map<String, dynamic> json) =>
      _$FoodTagCreateModelFromJson(json);

}

2. generate a ResApi client that use that model and run build runner

@RestApi()
abstract class CrudApi {
  factory CrudApi(Dio dio, {String? baseUrl}) = _CrudApi;

  @POST('/api/v1/my-model')
  Future<void> createAModel(@Body() MyModel body);

4. See error

MyModel must provide a `toJson()` method which return a Map.
It is programmer's responsibility to make sure the MyModel is properly serialized

Expected behavior If body is not Map force to add toJson() whether it has toJson() or not.