While fixing WFLY-21297 I noticed that the OIDC subsystem tests do NOT test the XML as the test method is overridden with no impl to always pass. When removed, the tests fail due to inconsistent read/write logic.

    @Override
    protected void compareXml(String configId, String original, String marshalled) {
        //
    }

e.g. here

https://github.com/wildfly/wildfly/blob/main/elytron-oidc-client/src/test/java/org/wildfly/extension/elytron/oidc/ElytronOidcClientSubsystemTestCase.java#L33-L36

https://github.com/wildfly/wildfly/blob/main/elytron-oidc-client/src/test/java/org/wildfly/extension/elytron/oidc/ElytronOidcClientSubsystemTransformerTestCase.java#L154-L157

https://github.com/wildfly/wildfly/blob/main/elytron-oidc-client/src/test/java/org/wildfly/extension/elytron/oidc/OidcTestCase.java#L140-L143