The Appointments+ plugin uses a class called Google_Auth_OAuth2 (among many others in the Goolge Authentication stream) that is also used by other plugins. This is causing me to have to disable Appointments+ to get the other plugins to work. I have already contacted the other plugin creators as well.
After a bunch of research, it looks like both Appointments+ and the other plugin are using what appears to be a standard implementation of Google Authentication libraries. At least, both plugins have pretty much the same folder structure and the same files when it comes to the 'Google' directory.
This means that Appointment+ will conflict with any plugin that uses the standard Google Authentication libraries.
I'm asking for Appointments+ to be updated so that it either checked to see if the Google Authentication classes already exist or to update the class names to be unique.