code: func keyFunc(name, namespace string, tr *authenticationv1.TokenRequest) string {
  	var exp int64
  	if tr.Spec.ExpirationSeconds != nil {
  		exp = *tr.Spec.ExpirationSeconds
  	}
  
  	var ref authenticationv1.BoundObjectReference
  	if tr.Spec.BoundObjectRef != nil {
  		ref = *tr.Spec.BoundObjectRef
  	}
  
  	return fmt.Sprintf("%q/%q/%#v/%#v/%#v", name, namespace, tr.Spec.Audiences, exp, ref)
  }
docs: // keys should be nonconfidential and safe to log