anchor.diff:        ],
       );
   
  +const _ubuntuLatest = 'ubuntu-latest';
  +
   /// Used as a place-holder so we can treat all jobs the same in certain
   /// workflows.
   class _SelfValidateJob implements HasStageName {
  
positive.code: 
  Map<String, dynamic> _selfValidateTaskConfig() => _githubJobYaml(
        selfValidateJobName,
        'ubuntu-latest',
        PackageFlavor.dart,
        'stable',
        [
  
negative.code:   String get _githubJobOs {
      switch (job.os) {
        case 'linux':
          return _ubuntuLatest;
        case 'windows':
          return 'windows-latest';
        case 'osx':
  