docs: public static Element getElementNode(final Element element, final DitaClass classValue) {
          final NodeList list = element.getChildNodes();
          for (int i = 0; i < list.getLength(); i++) {
              final Node node = list.item(i);
              if (node.getNodeType() == Node.ELEMENT_NODE) {
                  final Element child = (Element) node;
                  if (classValue.matches(child)) {
                      return child;
                  }
              }
          }
          return null;
      }