Update a calendar event

Update a calendar event for a patient. Attribute all_day must be true and end_at cannot be specified for plan-check-in event type. To mark a calendar event as 'completed', set completed_at and completed_by to desired values. To mark a completed calendar event as 'not completed', set completed_at and completed_by to null. Attendees can be added or removed, but response status cannot be updated. Use the calendar event response api for response status updates instead.