Jenkins ver. 1.483 Google Calendar plugin version 0.4
For example, this URL
http://www.google.com/calendar/feeds/3aijrqcp6bftmsen9ddhobmra8%40group.calendar.google.com/public/full
becomes
http://www.google.com/calendar/feeds/3aijrqcp6bftmsen9ddhobmra8%40group.calendar.google.com/private/full
Note the change from "public/full" to "private/full".
Then, in my failed Console Output:
... GCal: Preparing calendar update request... ERROR: GCal: Could not authenticate user ... http://www.google.com/calendar/feeds/3aijrqcp6bftmsen9ddhobmra8%40group.calendar.google.com/private/full