anchor.diff:      ..isAbstract = true;
     builder.superTypes.add(modelElement);
     builder.properties
  -    ..add((new PropertyBuilder()
  -          ..name = 'name'
  -          ..type = dartString)
  -        .build());
  +    ..add(new Property((b) => b
  +      ..name = 'name'
  +      ..type = dartString));
   
     return builder.build();
   }
  
positive.code:     ..name = 'ModelElement'
      ..isAbstract = true;
    builder.properties
      ..add((new PropertyBuilder()
            ..name = 'docComment'
            ..type = dartString
            ..isNullable = true)
          .build());
    return builder.build();
  }
  
  
negative.code:   final builder = new ValueClassBuilder()..name = 'TypeParameter';
    builder.superTypes.add(namedElement);
    builder.properties
      ..add(new Property((b) => b
        ..name = 'bound'
        ..type = classifier
        ..isNullable = true));
  
    return builder.build();
  }
  