Conflicting outputs: Potential outputs must be unique across all builders

[xErik]

Flutter 2.10.2 • channel stable • https://github.com/flutter/flutter.git
Framework • revision 097d3313d8 (9 days ago) • 2022-02-18 19:33:08 -0600
Engine • revision a83ed0e5e3
Tools • Dart 2.16.1 • DevTools 2.9.2

I am new to flutter and the answer probably is trivial.
I had been using json_annotation before but that package does not handle inheritance well.

CONFIG
I do not use class annotations (yet).

targets:
  $default:
    builders:
      dart_mappable:
        generate_for:
          - lib/bloc_novel/models.dart 
        options:
          - include: [Structure, NovelContainer, Item, Node, Beat, Scene, Step] 

RUNNING

flutter pub remove json_annotation
flutter clean
flutter pub get
flutter pub get super_annotations
flutter pub run build_runner build

RESULT

[SEVERE] Conflicting outputs
Both source_gen:combining_builder and super_annotations:super_annotations may output lib/bloc_novel/bloc.g.dart. Potential outputs must be unique across all builders. See https://github.com/dart-lang/build/blob/master/docs/faq.md#why-do-builders-need-unique-outputs
pub finished with exit code 78

TRIED

I tried to configure the builder to use a different naming scheme, but that resulted in the same error.

global_options:
  super_annotations:
    options:
      targets: [ mytarget ]