apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/service/NamespaceService.java/NamespaceService/transformItem2BO
class NamespaceService:  private ItemBO transformItem2BO(ItemDTO itemDTO, Map<String, String> releaseItems) {
    String key = itemDTO.getKey();
    ItemBO itemBO = new ItemBO();
    itemBO.setItem(itemDTO);
    String newValue = itemDTO.getValue();
    String oldValue = releaseItems.get(key);
    //new item or modified
    if (!StringUtils.isEmpty(key) && (!newValue.equals(oldValue))) {
      itemBO.setModified(true);
      itemBO.setOldValue(oldValue == null ? "" : oldValue);
      itemBO.setNewValue(newValue);
    }
    return itemBO;
  }