code: @Test public void decoratedModelShouldBeThreadSafe() throws Exception {
    final List<Transformer<WroModel>> modelTransformers=new ArrayList<Transformer<WroModel>>();
    modelTransformers.add(new WildcardExpanderModelTransformer());
    factory=DefaultWroModelFactoryDecorator.decorate(new GroovyModelFactory(){
      @Override protected InputStream getModelResourceAsStream() throws IOException {
        return TestGroovyModelFactory.class.getResourceAsStream("wro.groovy");
      }
    }
  ,modelTransformers);
    WroTestUtils.init(factory);
    final WroModel expectedModel=factory.create();
    WroTestUtils.runConcurrently(new ContextPropagatingCallable<Void>(new Callable<Void>(){
      @Override public Void call() throws Exception {
        Assert.assertEquals(expectedModel,factory.create());
        return null;
      }
    }
  ));
  }
  