code: private String getChildElementValueOfTopicmeta(final Element element, final DitaClass classValue) {
          if (element.hasChildNodes()) {
              final Element topicMeta = getElementNode(element, MAP_TOPICMETA);
              if (topicMeta != null) {
                  final Element elem = getElementNode(topicMeta, classValue);
                  if (elem != null) {
                      return getText(elem);
                  }
              }
          }
          return null;
      }
docs: get topicmeta's child(e.g navtitle, shortdesc) tag's value(text-only).
  
  @param element input element
  @return text value