private ReportingPeriod(OwnerId ownerId, TimePeriod timePeriod)
        {
            id              = Guid.NewGuid();
            this.ownerId    = ownerId;
            this.timePeriod = timePeriod;

            expenses = new HashSet <Expense>();
        }
 public Owner()
 {
     Id = new OwnerId(Guid.NewGuid());
 }
 public Owner(Guid id)
 {
     Id = new OwnerId(id);
 }