code: func getSourceAndObjectKey(attr admission.Attributes) string {
  	object := attr.GetObject()
  	if object == nil {
  		return ""
  	}
  	event, ok := object.(*api.Event)
  	if !ok {
  		return ""
  	}
  	return strings.Join([]string{
  		event.Source.Component,
  		event.Source.Host,
  		event.InvolvedObject.Kind,
  		event.InvolvedObject.Namespace,
  		event.InvolvedObject.Name,
  		string(event.InvolvedObject.UID),
  		event.InvolvedObject.APIVersion,
  	}, "")
  }
docs: // getSourceAndObjectKey returns a cache key that is based on the source+object of the event