anchor.diff:    final builder = new ValueClassBuilder()..name = 'ValueClass';
     builder.superTypes.add(valuableClass);
     builder.properties
  -    ..add((new PropertyBuilder()
  -          ..name = 'superTypes'
  -          // yuck: super type should be ValueClass but that blows up atm
  -          ..type = _createBuiltSet(valuableClass))
  -        .build());
  +    ..add(new Property((b) => b
  +      ..name = 'superTypes'
  +      // yuck: super type should be ValueClass but that blows up atm
  +      ..type = _createBuiltSet(valuableClass)));
     return builder.build();
   }
   
  
positive.code:   builder.superTypes.add(classifier);
  
    builder.properties
      ..add((new PropertyBuilder()
            ..name = 'base'
            ..type = classifier)
          .build())
      ..add((new PropertyBuilder()
            ..name = 'genericTypeValues'
            ..type = _createBuiltMap(typeParameter, classifier))
          .build());
  
    return builder.build();
  }
  
negative.code:     ..isAbstract = true;
    builder.superTypes.add(modelElement);
    builder.properties
      ..add(new Property((b) => b
        ..name = 'name'
        ..type = dartString));
  
    return builder.build();
  }
  