Fix Android handler

* Add in-app message handler listener
* Fix grouped notification parsing, not add to JSON if is an empty array
* Fix action id, make it optional
* Add notification open handler listener

Author: Jeasmine

android/src/main/java/com/onesignal/flutter/OneSignalPlugin.java

@@ -140,10 +140,11 @@ private void setAppId(MethodCall call, Result reply) {
     String appId = call.argument("appId");
     Context context = flutterRegistrar.activeContext();
 
+    OneSignal.setInAppMessageClickHandler(this);
     OneSignal.initWithContext(context);
     OneSignal.setAppId(appId);
 
-    if (hasSetRequiresPrivacyConsent)
+    if (hasSetRequiresPrivacyConsent && !OneSignal.userProvidedPrivacyConsent())
       this.waitingForUserPrivacyConsent = true;
     else
       this.addObservers();
@@ -156,6 +157,7 @@ private void addObservers() {
     OneSignal.addEmailSubscriptionObserver(this);
     OneSignal.addPermissionObserver(this);
     OneSignal.setNotificationWillShowInForegroundHandler(this);
+    OneSignal.setNotificationOpenedHandler(this);
   }
 
   private void setLogLevel(MethodCall call, Result reply) {

android/src/main/java/com/onesignal/flutter/OneSignalSerializer.java

@@ -106,7 +106,7 @@ static HashMap<String, Object> convertNotificationToMap(OSNotification notificat
 
         hash.put("androidNotificationId", notification.getAndroidNotificationId());
 
-        if (notification.getGroupedNotifications() != null) {
+        if (notification.getGroupedNotifications() != null && !notification.getGroupedNotifications().isEmpty()) {
             JSONArray payloadJsonArray = new JSONArray();
             for (OSNotification groupedNotification : notification.getGroupedNotifications())
                 payloadJsonArray.put(groupedNotification.toJSONObject());

lib/src/notification.dart

@@ -292,11 +292,11 @@ class OSNotificationAction {
 
   /// The ID of the button on your notification
   /// that the user tapped
-  late String actionId;
+  String? actionId;
 
   OSNotificationAction(Map<String, dynamic> json) {
     this.type = OSNotificationActionType.opened;
-    this.actionId = json['id'] as String;
+    this.actionId = json['id'] as String?;
 
     if (json.containsKey('type'))
       this.type = OSNotificationActionType.values[json['type'] as int];