@Override
    public void extract(final MapSession target, final String argument, final ValueCollector collector) {
        Optional.ofNullable(target.getAttribute(FindByIndexNameSessionRepository.PRINCIPAL_NAME_INDEX_NAME))
            .ifPresent(collector::addObject);
    }
This is {@link HazelcastSessionPrincipalNameExtractor}.

@author Misagh Moayyed
@since 6.6.0
support/cas-server-support-session-hazelcast/src/main/java/org/apereo/cas/config/HazelcastSessionPrincipalNameExtractor.java