docs: public static <ApiType> String deletionHandlingMetaNamespaceKeyFunc(ApiType object) {
      if (object instanceof DeltaFIFO.DeletedFinalStateUnknown) {
        DeltaFIFO.DeletedFinalStateUnknown deleteObj = (DeltaFIFO.DeletedFinalStateUnknown) object;
        return deleteObj.getKey();
      }
      return metaNamespaceKeyFunc(object);
    }