...
→ GET https://graph.microsoft.com/betav1.0/users/{external_id}/calendar/getschedule
...
→ POST https://graph.microsoft.com/betav1.0/users/{external_id}/events
...
→ POST https://graph.microsoft.com/betav1.0/me/events
Cancel a reservation
→ DELETE https://graph.microsoft.com/betav1.0/me/events
Get user reservations
→ GET https://graph.microsoft.com/betav1.0/me/calendar/calendarView
...