* Get configures XPath from the factory.
*/
@SuppressWarnings("unchecked")
private XPath getXPath(final Context ctx) throws SCXMLExpressionException {
if (!(ctx instanceof XPathContext)) {
throw new SCXMLExpressionException("XPathEvaluator needs XPathContext");
}
XPathContext xctx = (XPathContext) ctx;
factory.setXPathVariableResolver(xctx);
fnResolver.setContext(xctx);
XPath xpath = factory.newXPath();