ElytronAuthenticator.getPasswordAuthentication() cannot obtain PasswordFactory for Elytron related algorithms. It is caused by missing WildFlyElytronProvider (since Security::getProviders is used for obtaining providers) for PasswordFactory.getInstance in [1].

It results to hidden NoSuchAlgorithmException with message ELY08028: Invalid algorithm "clear" and stacktrace:

org.wildfly.security.password.PasswordFactory.getInstance(PasswordFactory.java:121)
org.wildfly.security.password.PasswordFactory.getInstance(PasswordFactory.java:75)
org.wildfly.security.auth.util.ElytronAuthenticator.getPasswordAuthentication(ElytronAuthenticator.java:92)
java.net.Authenticator.requestPasswordAuthentication(Authenticator.java:317)
...

It causes that even if element net-authenticator from Elytron client configuration file correctly sets ElytronAuthenticator as default Authenticator, it is not able to work with Elytron related algorithms.

[1] https://github.com/wildfly-security/wildfly-elytron/blob/4df6f4726b7cf070c4a49d0f05f115760132fe11/src/main/java/org/wildfly/security/auth/util/ElytronAuthenticator.java#L92