* @return a <tt>pom.xml</tt> <tt>groupId</tt>.
*/
String getGroupIdFromPom(Resource pomXml) {
try {
DocumentLoader docLoader = new DefaultDocumentLoader();
Document document = docLoader.loadDocument(new InputSource(pomXml.getInputStream()), null, null,
XmlValidationModeDetector.VALIDATION_NONE, false);
String groupId = DomUtils.getChildElementValueByTagName(document.getDocumentElement(), GROUP_ID_ELEM);
// no groupId specified, try the parent definition
if (groupId == null) {