code: public Optional<OPFItem> getItemByPath(String path)
    {
      return (items != null) ? items.getItemByPath(path) : Optional.<OPFItem> absent();
    }
docs: Search the list of item by path.
  
  @param id
  the path of the item to search
  @return an {@link Optional} containing the item of the given path if found,
  or {@link Optional#absent()}