void activate(long sessionId) {
        createLocalSessionFromDistributedApplicationPackage(sessionId);
        RemoteSession session = remoteSessionCache.get(sessionId);
        if (session == null) return;

        CompletionWaiter waiter = createSessionZooKeeperClient(sessionId).getActiveWaiter();
        log.log(Level.FINE, () -> session.logPre() + "Activating " + sessionId);
        applicationRepo.activateApplication(ensureApplicationLoaded(session), sessionId);
        log.log(Level.FINE, () -> session.logPre() + "Notifying " + waiter);
        notifyCompletion(waiter);
        log.log(Level.INFO, session.logPre() + "Session activated: " + sessionId);
    }
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