private static final Logger log = LoggerFactory.getLogger(InvalidatableRule.class);

    @Override
    public boolean isAvailable(Collection<?> itemIds) {
        if (itemIds.size() > 0 && itemIds.iterator().hasNext() && itemIds.iterator().next() instanceof JcrItemId) {
            JcrItemId jcrItemId = (JcrItemId) itemIds.iterator().next();
            Node node = SessionUtil.getNodeByIdentifier(jcrItemId.getWorkspace(), jcrItemId.getUuid());
            if (node != null) {
                try {
                    if (NodeUtil.isNodeType(node, DefaultForumManager.MESSAGE_NODETYPE)) {