code: protected static Element getChildElement(final Element parent, final String tagName) {
          List<Element> elements = getElements(parent, tagName);
          if (elements.size() > 0) {
              return elements.get(0);
          } else {
              return null;
          }
      }
docs: Get a single child element.
  @param parent The parent element
  @param tagName The child element name
  @return Element The first child element by that name