code: func (jobStrategy) PrepareForUpdate(ctx context.Context, obj, old runtime.Object) {
  	newJob := obj.(*batch.Job)
  	oldJob := old.(*batch.Job)
  	newJob.Status = oldJob.Status
  
  	if !utilfeature.DefaultFeatureGate.Enabled(features.TTLAfterFinished) && oldJob.Spec.TTLSecondsAfterFinished == nil {
  		newJob.Spec.TTLSecondsAfterFinished = nil
  	}
  
  	pod.DropDisabledTemplateFields(&newJob.Spec.Template, &oldJob.Spec.Template)
  }
docs: // PrepareForUpdate clears fields that are not allowed to be set by end users on update.