code: public void startDiff(String oldJar, String newJar) throws DiffException {
          Element tmp = doc.createElementNS(XML_URI, "diff");
          tmp.setAttribute( "old", oldJar);
          tmp.setAttribute( "new", newJar);
          doc.appendChild(tmp);
          currentNode = tmp;
      }
docs: Start the diff.
  This writes out the start of a &lt;diff&gt; node.
  
  @param oldJar ignored
  @param newJar ignored
  @throws DiffException when there is an underlying exception, e.g.
  writing to a file caused an IOException