code: public void setTimeZone(TimeZone timeZone) {
          if ( this.cronEx != null ) {
              this.cronEx.setTimeZone( timeZone );
          }
          this.timeZone = timeZone;
      }
docs: <p>
  Sets the time zone for which the <code>cronExpression</code> of this
  <code>CronTrigger</code> will be resolved.
  </p>
  
  <p>If {@link #setCronExpression(CronExpression)} is called after this
  method, the TimeZon setting on the CronExpression will "win".  However
  if {@link #setCronExpression(String)} is called after this method, the
  time zone applied by this method will remain in effect, since the
  String cron expression does not carry a time zone!