Retrieve list of defined roles in java ee 5

protected List<String> getSecurityRoles() {
	List<String> roles = new ArrayList<String>();
	ServletContext sc = this.getServletContext();
	InputStream is = sc.getResourceAsStream("/WEB-INF/web.xml");

	try {
		SAXReader reader = new SAXReader();
		Document doc = reader.read(is);

		Element webApp = doc.getRootElement();

		// Type safety warning:  dom4j doesn't use generics
		List<Element> roleElements = webApp.elements("security-role");
		for (Element roleEl : roleElements) {
			roles.add(roleEl.element("role-name").getText());
		}
	} catch (DocumentException e) {
		e.printStackTrace();
	}

	return roles;
}