// Check for organiztaion element. Must provide at least one... title gets ectracted from either
// the (optional) <title> element or the mandatory identifier attribute.
// This makes sure, at least a root node gets created in CPManifestTreeModel.
XPath meta = rootElement.createXPath("//ns:organization");
meta.setNamespaceURIs(nsuris);
Element orgaEl = (Element) meta.selectSingleNode(rootElement); // TODO: accept several organizations?
if (orgaEl == null) throw new AddingResourceException("resource.no.organisation");
// Check for at least one <item> element referencing a <resource>, which will serve as an entry point.
// This is mandatory, as we need an entry point as the user has the option of setting
// CPDisplayController to not display a menu at all, in which case the first <item>/<resource>