@Override
    public CasEvent save(final CasEvent event) throws Throwable {
        if (getEventRepositoryFilter().shouldSaveEvent(event)) {
            val result = saveInternal(event);
            Optional.ofNullable(applicationEventPublisher).ifPresent(publisher -> {
                val auditEvent = new AuditEvent(event.getPrincipalId(), event.getType(), (Map) event.getProperties());
                publisher.publishEvent(new AuditApplicationEvent(auditEvent));
            });
            return result;
        }
        return event;
    }
Field name to track principal linked to the event.
core/cas-server-core-events-api/src/main/java/org/apereo/cas/support/events/dao/AbstractCasEventRepository.java