Merge pull request igniterealtime#2137 from guusdk/OF-2537_pubsub-adv…

…ertise-multi-item

OF-2537: Advertise support for pubsub's 'multi-item' feature

xmppserver/src/main/java/org/jivesoftware/openfire/pubsub/PubSubModule.java

@@ -664,6 +664,8 @@ public Iterator<String> getFeatures(String name, String node, JID senderJID) {
             features.add("http://jabber.org/protocol/pubsub#subscription-options");
             // Publishing options are supported.
             features.add("http://jabber.org/protocol/pubsub#publish-options");
+            // Clients are allowed to set persist_items to true, and max_items to a value higher than 1, so this service can support multiple items.
+            features.add("http://jabber.org/protocol/pubsub#multi-items");
         }
         else if (name == null) {
             // Answer the features of a given node