code: public void addFooter(String key, String value)
    {
      if (headerOutSpecial(key, value)) {
        return;
      }
  
      _footerKeys.add(key);
      _footerValues.add(value);
    }
docs: Adds a new footer.  If an old footer with that name exists,
  both footers are output.
  
  @param key the footer key.
  @param value the footer value.