anchor.diff:  void main() {
     group('glTF', () {
       test('Invalid Collection', () async {
  -      final json = '{"asset": {"version": "2.0"},"samplers": {}}';
  +      const json = '{"asset": {"version": "2.0"},"samplers": {}}';
         final reader = new GltfJsonReader(
             new Stream<List<int>>.fromIterable([json.codeUnits]));
   
  
positive.code:     });
  
      test('Invalid Linkable Collection Element', () async {
        final json = '{"asset": {"version": "2.0"},"materials": [[], null]}';
        final reader = new GltfJsonReader(
            new Stream<List<int>>.fromIterable([json.codeUnits]));
  
  
negative.code:     });
  
      test('Invalid Collection Element', () async {
        const json = '{"asset": {"version": "2.0"},"samplers": [[], null]}';
        final reader = new GltfJsonReader(
            new Stream<List<int>>.fromIterable([json.codeUnits]));
  
  