Fix isSupported discovery of "Push Notifications"

Fixes SMACK-780.

smack-experimental/src/main/java/org/jivesoftware/smackx/push_notifications/PushNotificationsManager.java

@@ -87,13 +87,32 @@ public final class PushNotificationsManager extends Manager {
      * @throws XMPPErrorException
      * @throws NotConnectedException
      * @throws InterruptedException
+     * @deprecated Use {@link #isSupported()} instead.
      */
+    @Deprecated
+    // TODO: Remove in Smack 4.3
     public boolean isSupportedByServer()
             throws NoResponseException, XMPPErrorException, NotConnectedException, InterruptedException {
         return ServiceDiscoveryManager.getInstanceFor(connection())
                 .serverSupportsFeature(PushNotificationsElements.NAMESPACE);
     }
 
+    /**
+     * Returns true if Push Notifications are supported by this account.
+     *
+     * @return true if Push Notifications are supported by this account.
+     * @throws NoResponseException
+     * @throws XMPPErrorException
+     * @throws NotConnectedException
+     * @throws InterruptedException
+     * @since 4.2.2
+     */
+    public boolean isSupported()
+                    throws NoResponseException, XMPPErrorException, NotConnectedException, InterruptedException {
+        return ServiceDiscoveryManager.getInstanceFor(connection()).accountSupportsFeatures(
+                        PushNotificationsElements.NAMESPACE);
+    }
+
     /**
      * Enable push notifications.
      * 

smack-extensions/src/main/java/org/jivesoftware/smackx/disco/ServiceDiscoveryManager.java

@@ -52,6 +52,7 @@ import org.jivesoftware.smackx.disco.packet.DiscoverItems;
 import org.jivesoftware.smackx.xdata.packet.DataForm;
 
 import org.jxmpp.jid.DomainBareJid;
+import org.jxmpp.jid.EntityBareJid;
 import org.jxmpp.jid.Jid;
 import org.jxmpp.util.cache.Cache;
 import org.jxmpp.util.cache.ExpirationCache;
@@ -680,6 +681,41 @@ public final class ServiceDiscoveryManager extends Manager {
         return supportsFeatures(connection().getXMPPServiceDomain(), features);
     }
 
+    /**
+     * Check if the given features are supported by the connection account. This means that the discovery information
+     * lookup will be performed on the bare JID of the connection managed by this ServiceDiscoveryManager.
+     *
+     * @param features the features to check
+     * @return <code>true</code> if all features are supported by the connection account, <code>false</code> otherwise
+     * @throws NoResponseException
+     * @throws XMPPErrorException
+     * @throws NotConnectedException
+     * @throws InterruptedException
+     * @since 4.2.2
+     */
+    public boolean accountSupportsFeatures(CharSequence... features)
+                    throws NoResponseException, XMPPErrorException, NotConnectedException, InterruptedException {
+        return accountSupportsFeatures(Arrays.asList(features));
+    }
+
+    /**
+     * Check if the given collection of features are supported by the connection account. This means that the discovery
+     * information lookup will be performed on the bare JID of the connection managed by this ServiceDiscoveryManager.
+     *
+     * @param features a collection of features
+     * @return <code>true</code> if all features are supported by the connection account, <code>false</code> otherwise
+     * @throws NoResponseException
+     * @throws XMPPErrorException
+     * @throws NotConnectedException
+     * @throws InterruptedException
+     * @since 4.2.2
+     */
+    public boolean accountSupportsFeatures(Collection<? extends CharSequence> features)
+                    throws NoResponseException, XMPPErrorException, NotConnectedException, InterruptedException {
+        EntityBareJid accountJid = connection().getUser().asEntityBareJid();
+        return supportsFeatures(accountJid, features);
+    }
+
     /**
      * Queries the remote entity for it's features and returns true if the given feature is found.
      *