Added pubsub Node.modifySubscriptionsAsOwner with test

smack-extensions/src/main/java/org/jivesoftware/smackx/pubsub/Node.java

@@ -217,6 +217,31 @@ public abstract class Node {
         return subElem.getSubscriptions();
     }
 
+    /**
+     * Modify the subscriptions for this PubSub node as owner.
+     * <p>
+     * Note that the subscriptions are _not_ checked against the existing subscriptions
+     * since these are not cached (and indeed could change asynchronously)
+     * </p>
+     *
+     * @param changedSubs subscriptions that have changed
+     * @return <code>null</code> or a PubSub stanza with additional information on success.
+     * @throws NoResponseException
+     * @throws XMPPErrorException
+     * @throws NotConnectedException
+     * @throws InterruptedException
+     * @see <a href="https://xmpp.org/extensions/xep-0060.html#owner-subscriptions-modify">XEP-60 § 8.8.2 Modify Subscriptions</a>
+     * @since 4.3
+     */
+    public PubSub modifySubscriptionsAsOwner(List<Subscription> changedSubs)
+        throws NoResponseException, XMPPErrorException, NotConnectedException, InterruptedException {
+
+        PubSub pubSub = createPubsubPacket(Type.set,
+            new SubscriptionsExtension(getId(), changedSubs),
+            PubSubNamespace.OWNER);
+        return sendPubsubPacket(pubSub);
+    }
+
     /**
      * Get the affiliations of this node.
      *

smack-extensions/src/main/java/org/jivesoftware/smackx/pubsub/Subscription.java

@@ -56,6 +56,16 @@ public class Subscription extends NodeExtension {
         this(subscriptionJid, nodeId, null, null);
     }
 
+    /**
+     * Construct a subscription change request to the specified state.
+     *
+     * @param subscriptionJid The subscriber JID
+     * @param state The requested new state
+     */
+    public Subscription(Jid subscriptionJid, State state) {
+        this(subscriptionJid, null, null, state);
+    }
+
     /**
      * Constructs a representation of a subscription reply to the specified node 
      * and JID.  The server will have supplied the subscription id and current state.