@Override
    public void createNode( Node node )
    {
        log.debug( "Creating node: {}", node.getUniqueIdentifier() );
        CacheUtil.addValueToMultiValuedCache( serviceIdToNodesCache, node.getUniqueIdentifier().getServiceIdentifier(), node, HashSet::new );
    }
Cache that holds all published items (mapped by node ID).
xmppserver/src/main/java/org/jivesoftware/openfire/pubsub/InMemoryPubSubPersistenceProvider.java