Function validate_backup_on_schedule_delete 

pub fn validate_backup_on_schedule_delete(
    origin: Origin,
    value: Option<ScheduleDeletePolicy>,
) -> ValidationResult

origin: discovered Snapshots carry an empty spec; a stamped cascade policy on one is meaningless (their owner is a repository, not a schedule) and forbidden, like a non-Retain deletionPolicy. origin: adopted is forbidden for the same reason: an adopted row’s owner is the SnapshotPolicy it was re-attached to, never a SnapshotSchedule.