I've succesfully implemented the SSO using OIDC on Keycloak but in the plugin provided by Atlassian tgere is a wrong behaviour when logging out.

The log out button just logs out from the Atlassian application itself, instead it should call an end_session_endpoint like "https://idp.mydomain.ext/auth/realms/myrealm/protocol/openid-connect/logout?redirect_uri=[https://confluence.mydomain.ext/]"

The logout it will then be for all the platform using OIDC to authenticate. The actual behaviour gives the wrong impression you logged out meanwhile the OIDC token remains valid for all other platform using it

Regards

Marco Palumbo