code: void warn(String msg, Object[] args) throws TransformerException
    {
  
      String fmsg = XSLMessages.createXPATHWarning(msg, args);
      ErrorListener ehandler = this.getErrorListener();
  
      if (null != ehandler)
      {
        // TO DO: Need to get stylesheet Locator from here.
        ehandler.warning(new TransformerException(fmsg, m_sourceLocator));
      }
      else
      {
        // Should never happen.
        System.err.println(fmsg);
      }
    }
docs: Warn the user of a problem.
  
  @param msg An error msgkey that corresponds to one of the constants found
  in {@link org.apache.xpath.res.XPATHErrorResources}, which is
  a key for a format string.
  @param args An array of arguments represented in the format string, which
  may be null.
  
  @throws TransformerException if the current ErrorListoner determines to
  throw an exception.