static DocumentBuilder getPreprocessDocumentBuilder() throws ParserConfigurationException {
        DocumentBuilderFactory factory = createDocumentBuilderFactory();
        factory.setValidating(false);
        return factory.newDocumentBuilder();
    }
Creates a new XML document builder.

@return a new DocumentBuilder instance, or null if we fail to get one.
config-application-package/src/main/java/com/yahoo/config/application/Xml.java