boolean isKeywordMatched(PublishedItem publishedItem) {
        // Check if keyword was defined and it was not matched
        if (keyword != null && !keyword.isEmpty() && !publishedItem.containsKeyword(keyword)) {
            return false;
        }
        return true;
    }
Returns true if the published item matches the keyword filter specified in
the subscription. If no keyword was specified then answer true.

@param publishedItem the published item to send.
@return true if the published item matches the keyword filter specified in
        the subscription.
xmppserver/src/main/java/org/jivesoftware/openfire/pubsub/NodeSubscription.java