protected StringBuilder encodeBody(StringBuilder retval){
  retval.append(Integer.toString(expires));
  if (!parameters.isEmpty()) {
    retval.append(SEMICOLON);
    parameters.encode(retval);
  }
  return retval;
}

protected StringBuilder encodeBody ( StringBuilder retval ) { retval . append ( Integer . toString ( expires ) ) ; if ( ! parameters . isEmpty ( ) ) { retval . append ( SEMICOLON ) ; parameters . encode ( retval ) ; } return retval ; }
encode the header content into a string .
