code: protected ItemData putItem(ItemData item)
     {
        if (item.isNode())
        {
           return putNode((NodeData)item, ModifyChildOption.MODIFY);
        }
        else
        {
           return putProperty((PropertyData)item, ModifyChildOption.MODIFY);
        }
     }
docs: Internal put Item.
  
  @param item ItemData, new data to put in the cache
  @return ItemData, previous data or null