code: protected KeyHistory createKeyRecorededHistory(KeyHistory history)
      {
          KeyHistory result = null;
  
          if (history != null)
          {
              // For adjust message splited, use keyhistory's deepcopy.
              result = history.createDeepCopy();
          }
  
          return result;
      }
docs: Create keyhistory from original key history.<br>
  Use following situation.
  <ol>
  <li>Not used current message key.</li>
  <li>This class's key history function is not executed.</li>
  </ol>
  
  @param history original key history
  @return created key history