public bool Equals(IMainLogKey other) => other is SingleTimeEntryKey singleKey && timeEntryId == singleKey.timeEntryId;
public bool Equals(IMainLogKey other) => other is TimeEntriesGroupKey groupKey && groupId.Equals(groupKey.groupId);
public bool Equals(IMainLogKey other) => other is DayHeaderKey headerKey && date == headerKey.date;