Subscribing to all calendars of a user, only getting updates for a single one

Question

When I register a webhook for a users events as described here in the official docs and then insert an event in the non-default calender of that account (which I created before registering the webhook) I do not get a notification on the webhook url.

Only the "main calendar" (just named "Calendar") seems to have the hook attached.

My questions are:

1. How do I sync to all calendar events, or if this is not possible
2. How can I sync to specific calendar events

Answer 1

Turns out I interpreted the API docs wrong. I thought with the graph API, calendar webhooks were reworked, so you only subscribet to all calendars once and no longer to individual ones. So yeah.

Subscribing to specific calendars looks like this:

{
  "resource": "/me/calendars/{id}/events"
}