@Override
    public void loadNodes( PubSubService service )
    {
        log.debug( "Loading nodes for service: {}", service.getServiceID() );

        final Lock lock = serviceIdToNodesCache.getLock( service.getUniqueIdentifier() );
        lock.lock();
        try {
            final Set<Node> nodes = serviceIdToNodesCache.get(service.getUniqueIdentifier());
            if ( nodes != null )
            {
                nodes.forEach(service::addNode);
            }
        } finally {
            lock.unlock();
        }
    }
Cache that holds all published items (mapped by node ID).
xmppserver/src/main/java/org/jivesoftware/openfire/pubsub/InMemoryPubSubPersistenceProvider.java