private void DeleteAttendee(Attendee attendee)
        {
            int pos = _meeting.Attendees.IndexOf(x => x.EmailAddress.IsEqualTo(attendee.EmailAddress));
            _meeting.Attendees.RemoveAt(pos);

            PopulateAttendees();
        }
        private void AddAttendee(Attendee attendee)
        {
            if (_meeting.Attendees.Find(x => x.EmailAddress.IsEqualTo(attendee.EmailAddress)) == null)
            {
                _meeting.Attendees.Add(attendee);
            }

            PopulateAttendees();
        }
        private void UserSelected(User user)
        {
            var attendee = new Attendee
            {
                EmailAddress = new EmailAddress
                {
                    Address = user.UserPrincipalName,
                    Name = user.DisplayName
                }
            };

            AddAttendee(attendee);
        }
        private void ContactSelected(Contact contact)
        {
            var attendee = new Attendee
            {
                EmailAddress = contact.EmailAddresses[0]
            };

            AddAttendee(attendee);
        }
        private void DeleteAttendee(Attendee attendee)
        {
            if (attendee.IsOrganizer) return;

            int pos = Meeting.Attendees.IndexOf(x => x.EmailAddress.IsEqualTo(attendee.EmailAddress));

            Meeting.Attendees.RemoveAt(pos);

            PopulateAttendees();
        }