code: @Override
    public void setStartTime(Date startTime) {
  
      if (startTime == null) {
        throw new IllegalArgumentException("Start time cannot be null");
      }
  
      Date eTime = getEndTime();
      if (eTime != null && startTime != null && eTime.before(startTime)) {
        throw new IllegalArgumentException("End time cannot be before start time");
      }
  
      this.startTime = startTime;
    }
docs: Set the time at which the <code>SimpleTrigger</code> should occur.
  
  @exception IllegalArgumentException if startTime is <code>null</code>.