Errors during token validation because ADFS does not support introspection URL

[fabianlee]

I ran into several issues while trying to use Windows 2019 ADFS as the OAuth2 Authentication Server for a Flask based app using the flask-oidc module. One of the primary issues is that token validation errors out because there is no introspection endpoint URL.

If anyone runs into similar problems with ADFS, I created a proof-of-concept personal fork that supports Windows 2019 ADFS https://github.com/fabianlee/flask-oidc

I did not create a pull request because I did not do regression tests against the other supported Authentication servers (Google and Ipsilon), but it creates a good starting point for someone wanting this enhancement.