public ICollection <MeetingTimeDto> GetMeetingTimes(ICollection <int> userIds, DateTime from, DateTime to, int meetingDuration, int currentMeetingId) { foreach (int userId in userIds) { ValidationHelper.IntegerGreaterThanZero(userId, name: "User id"); } ValidationHelper.IntegerGreaterThanZero(currentMeetingId, name: "Meeting id"); return(_meetingsRepository.GetMeetingTimes(userIds, from, to, meetingDuration, currentMeetingId)); }