apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/service/ItemService.java/ItemService/loadItemById
class ItemService:  public ItemDTO loadItemById(Env env, long itemId) {
    ItemDTO item = itemAPI.loadItemById(env, itemId);
    if (item == null) {
      throw new BadRequestException("item not found for itemId " + itemId);
    }
    return item;
  }