`expand` not supported

Using the REST API I can pass `expand` to get nested data. This does not appear to be supported by the SDK. I'm able to work around it by doing:

```python
endpoint.params_map["all"].extend(["expand"])
endpoint.openapi_types.update({"expand": (str,)})
endpoint.location_map.update({"expand": "query"})
endpoint.attribute_map.update({"expand": "expand"})
```