private boolean isOldAndCanBeDeleted(Instant createTime) {
        Duration oneDay = Duration.ofDays(1);
        Duration expiry = Duration.ofSeconds(Math.max(sessionLifeTimeInSeconds(), oneDay.getSeconds()));
        return createTime.plus(expiry).isBefore(clock.instant());
    }
A session for which we don't have a watcher, i.e. hitherto unknown to us.

@param sessionId session id for the new session
configserver/src/main/java/com/yahoo/vespa/config/server/session/SessionRepository.java