我看老师在Service实现层 都是new一个map ，再往DAO传参数，为什么要这样写呢

@Transactional(propagation = Propagation.SUPPORTS)
@Override
public List<NewItemsVO> getSixNewItemsLazy(Integer rootCatId) {

   HashMap<String, Object> map = new HashMap<>();
   map.put("rootCatId", rootCatId);

   return categoryMapperCustom.getSixNewItemsLazy(map);
}