Before doing a post, SO does a GET by the vf module name and that returns 405.

It should return an empty response similar to this:

{
"template_type": "HEAT",
"workload_status_reason":

{ "stacks": []  key point, query by stack name returns and empty list – since we’re creating, this is expectedgg }

,
"workload_status": "GET_COMPLETE",
"workload_id": ""
}