https://github.com/kubernetes/kubernetes/blob/87f9429087d4e31201412548517d36e83abebc8d/pkg/controller/cronjob/cronjob_controller.go#L190-L344

cronjob_controller.go

// from: https://github.com/kubernetes/kubernetes/blob/87f9429087d4e31201412548517d36e83abebc8d/pkg/controller/cronjob/cronjob_controller.go#L190-L344

childrenJobs := make(map[types.UID]bool)
for _, j := range js {
	childrenJobs[j.ObjectMeta.UID] = true
	found := inActiveList(*sj, j.ObjectMeta.UID)
	if !found && !IsJobFinished(&j) {
		recorder.Eventf(sj, v1.EventTypeWarning, "UnexpectedJob", "Saw a job that the controller did not create or forgot: %v", j.Name)
		// We found an unfinished job that has us as the parent, but it is not in our Active list.
		// This could happen if we crashed right after creating the Job and before updating the status,
		// or if our jobs list is newer than our sj status after a relist, or if someone intentionally created
		// a job that they wanted us to adopt.

		// TODO: maybe handle the adoption case?  Concurrency/suspend rules will not apply in that case, obviously, since we can't
		// stop users from creating jobs if they have permission.  It is assumed that if a
		// user has permission to create a job within a namespace, then they have permission to make any scheduledJob
		// in the same namespace "adopt" that job.  ReplicaSets and their Pods work the same way.
		// TBS: how to update sj.Status.LastScheduleTime if the adopted job is newer than any we knew about?
	} else if found && IsJobFinished(&j) {
		deleteFromActiveList(sj, j.ObjectMeta.UID)
		// TODO: event to call out failure vs success.
		recorder.Eventf(sj, v1.EventTypeNormal, "SawCompletedJob", "Saw completed job: %v", j.Name)
	}
}