/**
* Return values of all {@code <jaxb:class ref="..." />} attributes.
*/
private Set<String> getClassReferencesFromEpisodeFile(String episodeFile) throws SAXException {
DOMForest forest = new DOMForest(new XMLSchemaInternalizationLogic(), new Options());
Document episodeDocument = forest.parse(new InputSource(episodeFile), true);
NodeList nodeList = episodeDocument.getElementsByTagNameNS(Const.JAXB_NSURI, "class");
Set<String> classReferences = new HashSet<String>();