After successful authentication during a call to HttpServletRequest.login(username,password) the SecurityRealm receives a 

org.wildfly.security.auth.server.event.RealmFailedAuthenticationEvent

This appears to be due to org.wildfly.security.http.HttpAuthenticator.login not calling succeed() on the ServerAuthenticationContext.

adding 

authenticationContext.succeed();

to the login method prior to returning the authorizedIdentity appears to fix the problem.