I couldn't find any official documentation specifying what each parameter to a `sla_miss_callback` callable are. This would be a great addition to know how to properly format the messages sent.
airflow/models/dag.py
self,
        task_id: str,
        execution_date: datetime,
        state: State,
        upstream: Optional[bool] = False,
        downstream: Optional[bool] = False,
        future: Optional[bool] = False,
        past: Optional[bool] = False,
        commit: Optional[bool] = True,
        session=None,