@Override
  public void writeExternal(Element element) {
    if (hasDefaultValues()) {
      return;
    }

    for (String value : this) {
      if (value != null) {
        final Element item = new Element(ITEM);
        item.setAttribute(VALUE, StringUtil.escapeXmlEntities(value));
        element.addContent(item);
      }
    }
  }
@Override
  public void writeExternal(Element element)