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