At some point I added my Google account credentials to
gnome-calendar but I can't recall when. I don't believe that I manually opened the application and explicitly added this account, as I don't ever use it.
I must have been prompted at some point to add my Google account somewhere. When might this prompt have appeared?
This all originated from my receiving Google Calendar reminders from the
evolution-alarm-notify ("Reminder" panel icon). It receives this information from the
evolution-data-server for which I have to manage my credentials through the
gnome-calendar application. It took an unpleasant amount of time and effort to finally track this down.
I am using Fedora 30 with MATE Desktop and I installed all of my packages manually from a minimal install. This was most likely a dependency package inherited from my trying out GNOME Desktop so this wasn't anything related to a bootable Live desktop image or the graphical installer.
When might GNOME/gnome-calendar have asked for my Google account credentials?