`on_event` is deprecated, use `lifespan` event handlers instead.

        Read more about it in the
        [FastAPI docs for Lifespan Events](https://fastapi.tiangolo.com/advanced/events/#alternative-events-deprecated).
        """

        def decorator(func: DecoratedCallable) -> DecoratedCallable:
            self.add_event_handler(event_type, func)
            return func