String (String uri, XmlElement context) { final BidirectionalMap<String, String> bidiMap = new BidirectionalMap<>(); bidiMap.putAll(Namespace.makeMap(myNamespaceTableModel.getNamespaces())); final List<String> list = bidiMap.getKeysByValue(uri); return list != null && list.size() > 0 ? list.get(0) : null; }