This bug was discovered during test development for the OIDC Step-Up Authentication feature https://issues.redhat.com/browse/QUARKUS-6260 .

When an OIDC provider, such as Keycloak, returns a single Authentication Context Class Reference (ACR) value as a String instead of a JsonArray, the step-up authentication mechanism does not behave as expected.

Detailed description is in the upstream issue here : https://github.com/quarkusio/quarkus/issues/50364

The fix has been done (also merged in main)  here : https://github.com/quarkusio/quarkus/pull/50367