/** {@inheritDoc} */
  protected void marshallElementContent(XMLObject xmlObject, Element domElement)
      throws MarshallingException {
    SignableSimpleXMLObject simpleXMLObject = (SignableSimpleXMLObject) xmlObject;

    if (simpleXMLObject.getValue() != null) {
      domElement.setTextContent(simpleXMLObject.getValue());
    }
  }
  /** {@inheritDoc} */
  protected void marshallAttributes(XMLObject xmlObject, Element domElement)
      throws MarshallingException {
    SignableSimpleXMLObject simpleXMLObject = (SignableSimpleXMLObject) xmlObject;

    if (simpleXMLObject.getId() != null) {
      domElement.setAttributeNS(
          null, SignableSimpleXMLObject.ID_ATTRIB_NAME, simpleXMLObject.getId());
      domElement.setIdAttributeNS(null, SignableSimpleXMLObject.ID_ATTRIB_NAME, true);
    }

    XMLHelper.marshallAttributeMap(simpleXMLObject.getUnknownAttributes(), domElement);
  }