private void addMapping(String actionId, KeyStroke[] keyStrokes) throws IOException {
      XmlAttributes attributes = new XmlAttributes();
      attributes.add(ID_ATTRIBUTE, actionId);

      LOGGER.trace(
          "     Writing mapping of " + actionId + " to " + keyStrokes[0] + " and " + keyStrokes[1]);

      if (keyStrokes[0] != null)
        attributes.add(
            PRIMARY_KEYSTROKE_ATTRIBUTE, KeyStrokeUtils.getKeyStrokeRepresentation(keyStrokes[0]));

      if (keyStrokes[1] != null)
        attributes.add(
            ALTERNATE_KEYSTROKE_ATTRIBUTE,
            KeyStrokeUtils.getKeyStrokeRepresentation(keyStrokes[1]));

      writer.writeStandAloneElement(ACTION_ELEMENT, attributes);
    }