public void SetStartTimeBackward(DueTime startTime)
{
if (_productionOrderOperation.IsReadOnly)
{
throw new MrpRunException("A readOnly entity cannot be changed anymore.");
}
DueTime transitionTime =
new DueTime(TransitionTimer.CalculateTransitionTime(GetDuration()));
// startBackwards
DueTime startTimeOfOperation = startTime.Plus(transitionTime);
_productionOrderOperation.StartBackward = startTimeOfOperation.GetValue();
// endBackwards
_productionOrderOperation.EndBackward =
startTimeOfOperation.GetValue() + GetDuration().GetValue();
}