@Override
    public void createSubscription(Node node, NodeSubscription subscription) {
        log.debug( "Creating node subscription for owner {} to node {} (subscription ID: {})", subscription.getOwner(), node.getUniqueIdentifier(), subscription.getID() );

        final List<NodeOperation> operations = nodesToProcess.computeIfAbsent( node.getUniqueIdentifier(), id -> new ArrayList<>() );
        final NodeOperation operation = NodeOperation.createSubscription( node, subscription );
        operations.add( operation );
    }
Cache for recently accessed published items.
xmppserver/src/main/java/org/jivesoftware/openfire/pubsub/CachingPubsubPersistenceProvider.java