final SchemaFactory schemaFactory = SchemaFactory.newInstance(XMLConstants.RELAXNG_NS_URI);
        if (!external) {
            disableExternalResources(schemaFactory);
        }
        return schemaFactory;
    }

    private static void disableExternalResources(final SchemaFactory schemaFactory) {
        try {
            schemaFactory.setProperty(XMLConstants.ACCESS_EXTERNAL_SCHEMA, "");

            final SAXParser parser = spfactory.newSAXParser();
            disableExternalResources(parser);
            parser.parse(in, handler);
        } catch (final Exception e) {
            throw new SitemapsException("Could not parse XML Sitemaps.", e);
        }
        return handler.getSitemapSet();
    }

    protected void disableExternalResources(final SAXParser parser) throws SAXNotRecognizedException, SAXNotSupportedException {