- TimePeriodGroup duration is now optional
- TimePeriodGroup duration is now optional

UberJason/DateTools,michal-olszewski/DateTools,michal-olszewski/DateTools,Dashlane/DateTools,MatthewYork/DateTools,UberJason/DateTools,Dashlane/DateTools,Dashlane/DateTools,UberJason/DateTools,michal-olszewski/DateTools,MatthewYork/DateTools,MatthewYork/DateTools