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
"""Exclude tasks not included in the subdag from the given TaskGroup."""
            copied = copy.copy(group)
            copied.used_group_ids = set(copied.used_group_ids)
            copied._parent_group = parent_group
            copied.children = {}
            for child in group.children.values():
                if isinstance(child, BaseOperator):
                    if child.task_id in dag.task_dict:
                        copied.children[child.task_id] = dag.task_dict[child.task_id]
                    else:
                        copied.used_group_ids.discard(child.task_id)
                else:
                    filtered_child = filter_task_group(child, copied)
                    
                    if filtered_child.children:
                        copied.children[child.group_id] = filtered_child
            return copied
        dag._task_group = filter_task_group(self._task_group, None)
        
        
        subdag_task_groups = dag.task_group.get_task_group_dict()
        for group in subdag_task_groups.values():
            group.upstream_group_ids = group.upstream_group_ids.intersection(subdag_task_groups.keys())
            group.downstream_group_ids = group.downstream_group_ids.intersection(subdag_task_groups.keys())
            group.upstream_task_ids = group.upstream_task_ids.intersection(dag.task_dict.keys())
            group.downstream_task_ids = group.downstream_task_ids.intersection(dag.task_dict.keys())
        for t in dag.tasks: