anchor.diff:    static const E a = E._(0);
     static const E b = E._(1);
     static const E c = E._(2);
  -  const E._(int x);
  +  final int x;
  +  const E._(this.x);
   }
   ''');
       await assertHasFixWithFilter('''
  
positive.code:   static const E a = E._(0);
    static const E b = E._(1);
    static const E c = E._(2);
    const E._(int x);
  }
  ''');
    }
  
negative.code:   static const E a = E._(0);
    static const E b = E._(1);
    static const E c = E._(2);
    final int x;
    const E._(this.x);
  }
  ''');
      await assertHasFixWithFilter('''
  