code: <E extends Entity> void registerStaticEntityFactory(EntityFactory<E, ?> staticEntityFactory) {
      String entityTypeId = staticEntityFactory.getEntityTypeId();
      staticEntityFactoryMap.put(entityTypeId, staticEntityFactory);
    }
docs: Registers a static entity factory
  
  @param staticEntityFactory static entity factory
  @param <E> static entity type (e.g. Tag, Language, Package)