Hello folks - 
I have successfully used the v2 API against TWC to download model elements and to change them via the commits POST endpoint. However, when I consult the v2 API cookbook on creating new model elements, it tells me to delete any references to model identity (DataIdentity, @id). All well and good since there is no ID on the server yet. However, when I do this I get jackson XML errors saying that a key cannot be found in my JSON. When I keep the keys but leave the fields blank, I get null errors. Here is what I am trying to POST via requests when I get the errors.

commit_body = {
 "@type": "Commit",
 "description": "Add new element.",
 "change": [
   {
     "@type": "DataVersion",
     "payload": {
        "@type": "PartUsage",
        "declaredName": "Test Part"
      }
   }
 ]
}

This, as a change, is successful:
commit_body = {
 "@type": "Commit",
 "description": "Change element name.",
 "change": [
   {
      "@id": "some uuid4 id",
     "@type": "DataVersion",
     "payload": {
        "@type": "PartUsage",
        "declaredName": "Test Part"
      },
      "identity": {
        "@id": "some uuid4 id",
        "@type": "DataIdentity"
      }
   }
 ]
}

Is there a field that is being expected to tell the API that the element has no ID since it is being created?