code: func ValidateEvent(event *api.Event) field.ErrorList {
  	allErrs := field.ErrorList{}
  	// There is no namespace required for node.
  	// However, older client code accidentally sets event.Namespace
  	// to api.NamespaceDefault, so we accept that too, but "" is preferred.
  	if event.InvolvedObject.Kind == "Node" &&
  		event.Namespace != api.NamespaceDefault &&
  		event.Namespace != "" {
  		allErrs = append(allErrs, field.Invalid(field.NewPath("involvedObject", "namespace"), event.InvolvedObject.Namespace, "not allowed for node"))
  	}
  	if event.InvolvedObject.Kind != "Node" &&
  		event.Namespace != event.InvolvedObject.Namespace {
  		allErrs = append(allErrs, field.Invalid(field.NewPath("involvedObject", "namespace"), event.InvolvedObject.Namespace, "does not match involvedObject"))
  	}
  	if !validation.IsDNS1123Subdomain(event.Namespace) {
  		allErrs = append(allErrs, field.Invalid(field.NewPath("namespace"), event.Namespace, ""))
  	}
  	return allErrs
  }
docs: // ValidateEvent makes sure that the event makes sense.