code: public void contains(ClassInfo info) throws DiffException {
          Element tmp = doc.createElementNS(XML_URI, "class");
          tmp.setAttribute("name", info.getName());
          currentNode.appendChild(tmp);
      }
docs: Add a contained class.
  
  @param info information about a class
  @throws DiffException when there is an underlying exception, e.g.
  writing to a file caused an IOException