code: void removeNonExistingSystemEntityTypes() {
      // get all system entities
      List<EntityType> removedSystemEntityMetas =
          dataService
              .findAll(ENTITY_TYPE_META_DATA, EntityType.class)
              .filter(EntityTypeUtils::isSystemEntity)
              .filter(this::isNotExists)
              .collect(toList());
  
      dataService.getMeta().deleteEntityType(removedSystemEntityMetas);
      removedSystemEntityMetas.forEach(
          entityType ->
              mutableAclClassService.deleteAclClass(EntityIdentityUtils.toType(entityType)));
    }
docs: Package-private for testability