remove workaround per #651

Author: n2ygk

example/views.py

@@ -208,18 +208,7 @@ def get_queryset(self, *args, **kwargs):
         return super(CommentViewSet, self).get_queryset()
 
 
-class TestModelViewSet(PreloadIncludesMixin, RelatedMixin, viewsets.ModelViewSet):
-    """
-    TODO: this is a temporary workaround since AutoPreloadMixin and PreloadIncludesMixin
-    conflict with each other for polymorphic viewsets.
-    See https://github.com/django-json-api/django-rest-framework-json-api/pull/643
-    DJA's views.ModelViewSet has both AutoPreloadMixin and PreloadIncludesMixin.
-    """
-    http_method_names = ['get', 'post', 'patch', 'delete', 'head', 'options']
-
-
-# class CompanyViewset(PreloadIncludesMixin, viewsets.ModelViewSet):
-class CompanyViewset(TestModelViewSet):
+class CompanyViewset(ModelViewSet):
     queryset = Company.objects.all()
     serializer_class = CompanySerializer