The undefined serialization behavior warning can probably be fixed by implementing the deepObject serialization style (as described in https://swagger.io/docs/specification/serialization), but it needs a lot more investigation and refactoring that is out of scope for this partial revert to fix the current mess.
Fixes https://github.com/nextcloud/openapi-extractor/issues/144
The undefined serialization behavior warning can probably be fixed by implementing the deepObject serialization style (as described in https://swagger.io/docs/specification/serialization), but it needs a lot more investigation and refactoring that is out of scope for this partial revert to fix the current mess.