Add support for IoT Friend approvals

This adds supports for an experimental protocol flow where a pending
friend request's decission is later on deliverd to the requestor after
the owner made its decission.

smack-im/src/main/java/org/jivesoftware/smack/roster/Roster.java

@@ -681,6 +681,7 @@ public final class Roster extends Manager {
         Objects.requireNonNull(subscribeListener, "SubscribeListener argument must not be null");
         if (subscriptionMode != SubscriptionMode.manual) {
             previousSubscriptionMode = subscriptionMode;
+            subscriptionMode = SubscriptionMode.manual;
         }
         return subscribeListeners.add(subscribeListener);
     }
@@ -1228,6 +1229,7 @@ public final class Roster extends Manager {
             RosterPacket.Item oldItem = RosterEntry.toRosterItem(oldEntry);
             if (!oldEntry.equalsDeep(entry) || !item.getGroupNames().equals(oldItem.getGroupNames())) {
                 updatedEntries.add(item.getJid());
+                oldEntry.updateItem(item);
             } else {
                 // Record the entry as unchanged, so that it doesn't end up as deleted entry
                 unchangedEntries.add(item.getJid());

smack-im/src/main/java/org/jivesoftware/smack/roster/RosterEntry.java

@@ -28,6 +28,8 @@ import org.jivesoftware.smack.XMPPConnection;
 import org.jivesoftware.smack.SmackException.NotConnectedException;
 import org.jivesoftware.smack.XMPPException.XMPPErrorException;
 import org.jivesoftware.smack.packet.IQ;
+import org.jivesoftware.smack.packet.Presence;
+import org.jivesoftware.smack.packet.Presence.Type;
 import org.jivesoftware.smack.roster.packet.RosterPacket;
 import org.jxmpp.jid.BareJid;
 
@@ -41,7 +43,7 @@ import org.jxmpp.jid.BareJid;
  */
 public final class RosterEntry extends Manager {
 
-    private final RosterPacket.Item item;
+    private RosterPacket.Item item;
     final private Roster roster;
 
     /**
@@ -120,10 +122,9 @@ public final class RosterEntry extends Manager {
      * @param type the subscription type.
      * @param subscriptionPending TODO
      */
-    void updateState(String name, RosterPacket.ItemType type, boolean subscriptionPending) {
-        item.setName(name);
-        item.setItemType(type);
-        item.setSubscriptionPending(subscriptionPending);
+    void updateItem(RosterPacket.Item item) {
+        assert(item != null);
+        this.item = item;
     }
 
     /**
@@ -209,6 +210,18 @@ public final class RosterEntry extends Manager {
         }
     }
 
+    /**
+     * Cancel the presence subscription the XMPP entity representing this roster entry has with us.
+     * 
+     * @throws NotConnectedException
+     * @throws InterruptedException
+     * @since 4.2
+     */
+    public void cancelSubscription() throws NotConnectedException, InterruptedException {
+        Presence unsubscribed = new Presence(item.getJid(), Type.unsubscribed);
+        connection().sendStanza(unsubscribed);
+    }
+
     public String toString() {
         StringBuilder buf = new StringBuilder();
         if (getName() != null) {

smack-im/src/main/java/org/jivesoftware/smack/roster/RosterUtil.java

@@ -25,6 +25,7 @@ import java.util.concurrent.locks.ReentrantLock;
 
 import org.jivesoftware.smack.SmackException.NotConnectedException;
 import org.jivesoftware.smack.SmackException.NotLoggedInException;
+import org.jivesoftware.smack.XMPPConnection;
 import org.jxmpp.jid.BareJid;
 import org.jxmpp.jid.Jid;
 
@@ -90,4 +91,24 @@ public class RosterUtil {
             roster.sendSubscriptionRequest(jid);
         }
     }
+
+    public static void ensureNotSubscribedToEachOther(XMPPConnection connectionOne, XMPPConnection connectionTwo)
+            throws NotConnectedException, InterruptedException {
+        final Roster rosterOne = Roster.getInstanceFor(connectionOne);
+        final BareJid jidOne = connectionOne.getUser().asBareJid();
+        final Roster rosterTwo = Roster.getInstanceFor(connectionTwo);
+        final BareJid jidTwo = connectionTwo.getUser().asBareJid();
+
+        ensureNotSubscribed(rosterOne, jidTwo);
+        ensureNotSubscribed(rosterTwo, jidOne);
+    }
+
+    public static void ensureNotSubscribed(Roster roster, BareJid jid)
+            throws NotConnectedException, InterruptedException {
+        RosterEntry entry = roster.getEntry(jid);
+        if (entry != null && entry.canSeeMyPresence()) {
+            entry.cancelSubscription();
+        }
+    }
+
 }

smack-im/src/main/java/org/jivesoftware/smack/roster/packet/RosterPacket.java

@@ -108,6 +108,7 @@ public class RosterPacket extends IQ {
      * A roster item, which consists of a JID, their name, the type of subscription, and
      * the groups the roster item belongs to.
      */
+    // TODO Make this class immutable.
     public static class Item implements NamedElement {
 
         /**
@@ -124,6 +125,7 @@ public class RosterPacket extends IQ {
          */
         private boolean subscriptionPending;
 
+        // TODO Make immutable. 
         private String name;
         private ItemType itemType = ItemType.none;
         private boolean approved;