OpenID/Keycloak Integration Issues

Hello Everyone! First of all, I don't know if Zeppelin can be integrated with Keycloak, but I have come across https://github.com/apache/zeppelin/pull/2373 which describes the keycloak integration setup by means of shiro + pac4j oidc.

I have followed the guidelines and have copied the list of jars to the zeppelin lib folder (list of jars attached) and have also updated the `shiro.ini` file with the required oidc,pac4j parameters. The setup works and I am successfully getting redirected to keycloak login page, the login part also works fine and I could see login_successful messages in the keycloak logs, but it throws a http/500 error at the time of redirect after the login as seen in the attached screenshot, I would appreciate if someone could help me to fix this issue.

Attached is my shiro.ini, zeppelin.log and other files, please let me know if you need any other details. Thanks!