@Override
    public Principal fetch(final CasSimpleMultifactorTokenCredential tokenCredential) {
        return Optional.ofNullable(getMultifactorAuthenticationTicket(tokenCredential))
            .map(this::getPrincipalFromTicket)
            .orElse(null);
    }
This is {@link DefaultCasSimpleMultifactorAuthenticationService}.

@author Misagh Moayyed
@since 6.6.0
support/cas-server-support-simple-mfa-core/src/main/java/org/apereo/cas/mfa/simple/validation/DefaultCasSimpleMultifactorAuthenticationService.java