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
if include_parentdag and self.is_subdag and self.parent_dag is not None:
            p_dag = self.parent_dag.partial_subset(
                task_ids_or_regex=r"^{}$".format(self.dag_id.split('.')[1]),
                include_upstream=False,
                include_downstream=True,
            )
            result.update(
                p_dag._get_task_instances(
                    task_ids=task_ids,
                    start_date=start_date,
                    end_date=end_date,
                    run_id=None,
                    state=state,
                    include_subdags=include_subdags,
                    include_parentdag=False,
                    include_dependent_dags=include_dependent_dags,
                    as_pk_tuple=True,
                    exclude_task_ids=exclude_task_ids,
                    session=session,
                    dag_bag=dag_bag,
                    recursion_depth=recursion_depth,
                    max_recursion_depth=max_recursion_depth,
                    visited_external_tis=visited_external_tis,
                )
            )
        if include_dependent_dags:
            
            from airflow.sensors.external_task import ExternalTaskMarker
            query = tis