Merge pull request #1603 from OneSignal/fix/groupless_heads_up_redisplay

[Fix] groupless heads-up style notifications from redisplaying previous

Author: jkasten2

OneSignalSDK/onesignal/src/main/java/com/onesignal/OneSignalNotificationManager.java

@@ -100,19 +100,16 @@ static ArrayList<StatusBarNotification> getActiveGrouplessNotifications(Context
     /**
      * All groupless notifications are assigned the GROUPLESS_SUMMARY_KEY and notify() is called
      */
-    @RequiresApi(api = Build.VERSION_CODES.M)
+    @RequiresApi(api = Build.VERSION_CODES.N)
     static void assignGrouplessNotifications(Context context, ArrayList<StatusBarNotification> grouplessNotifs) {
         for (StatusBarNotification grouplessNotif : grouplessNotifs) {
-            Notification.Builder grouplessNotifBuilder;
-            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
-                grouplessNotifBuilder = Notification.Builder.recoverBuilder(context, grouplessNotif.getNotification());
-            } else {
-                grouplessNotifBuilder = new Notification.Builder(context);
-            }
+            Notification.Builder grouplessNotifBuilder =
+                Notification.Builder.recoverBuilder(context, grouplessNotif.getNotification());
 
             // Recreate the notification but with the groupless key instead
             Notification notif = grouplessNotifBuilder
                     .setGroup(GROUPLESS_SUMMARY_KEY)
+                    .setOnlyAlertOnce(true)
                     .build();
 
             NotificationManagerCompat.from(context).notify(grouplessNotif.getId(), notif);