If accessed using an OAuth access token, the APPS_WRITE scope is required.
value must be Bearer <token> where <token> is api key prefixed with cal_, managed user access token, or OAuth access token
The calendar service you want to integrate, as returned by the /calendars endpoint
apple_calendar, google_calendar, office365_calendar "apple_calendar"
Unique identifier used to represent the specific calendar, as returned by the /calendars endpoint
"https://caldav.icloud.com/26962146906/calendars/1644422A-1945-4438-BBC0-4F0Q23A57R7S/"