https://apidata.googleusercontent.com/caldav/v2/<YOUR-CALENDAR-ID>/events
Calendar ID can be found at calendar settings.
Examples:
https://apidata.googleusercontent.com/caldav/v2/dzagashev@gmail.com/events
https://apidata.googleusercontent.com/caldav/v2/addressbook#contacts@group.v.calendar.google.com/events
https://apidata.googleusercontent.com/caldav/v2/ru.ukrainian#holiday@group.v.calendar.google.com/events