/**
  * Retrieve the previous timezone transition for the timezone tz
  * before date date.
  *
  * @param   util.TimeZone tz
  * @param   util.Date date
  * @return  util.TimeZoneTransition
  * @throws  lang.IllegalArgumentException if timezone has no transitions
  */
 public static function previousTransition(TimeZone $tz, Date $date)
 {
     $t = new self($tz, $date);
     $t->previous();
     return $t;
 }