public static Optional<String> getOptionalAttribute(Element element, String name) {
        return Optional.ofNullable(element.getAttribute(name)).filter(s -> !s.isEmpty());
    }
Creates a new XML document builder.

@return a new DocumentBuilder instance, or null if we fail to get one.
config-model/src/main/java/com/yahoo/config/model/builder/xml/XmlHelper.java