code: public int compareTo (final ITrigger other)
    {
  
      if (other.getKey () == null && getKey () == null)
        return 0;
      if (other.getKey () == null)
        return -1;
      if (getKey () == null)
        return 1;
  
      return getKey ().compareTo (other.getKey ());
    }
docs: <p>
  Compare the next fire time of this <code>Trigger</code> to that of another
  by comparing their keys, or in other words, sorts them according to the
  natural (i.e. alphabetical) order of their keys.
  </p>