In following patch was introduced bug:

https://github.com/wildfly-security/wildfly-elytron/pull/851/files#diff-dc83c9f75c0f78bbdfd49f49d56514faR332

DigestSaslClient requests URP digest for default userName (authzid), not for authentication name (from NameCallback).
Code is ok for server side, but not for client side, where credential callback params should require name obtained by NameCallback.