* Add support for Swagger UI [initOauth](https://github.com/swagger-api/swagger-ui/blob/master/docs/usage/oauth2.md) settings with the parameter `swagger_ui_init_oauth`. PR [#499](https://github.com/tiangolo/fastapi/pull/499) by [@zamiramir](https://github.com/zamiramir).
## 0.39.0
* Allow path parameters to have default values (e.g. `None`) and discard them instead of raising an error.