This issue was reported in WildFly google group discussion:

https://groups.google.com/g/wildfly/c/R-6-m0IzgiY/m/DKlwSntTBAAJ?utm_medium=email&utm_source=footer

I noticed that the jboss-client.jar since I think two versions ago doesn't include the LocalUserClient anymore (package org.wildfly.security.sasl.localuser is missing).

We should fix client/shade/pom.xml to include wildfly-elytron-sasl-localuser artifact.