[flutter_local_notifications] fixed issue with null schedule mode where recurring notifications would fail to be scheduled as a result (#2041)

* fixed issue with null schedule mode

* Google Java Format

* added more details on explanation of how null schedule mode occurred

---------

Co-authored-by: github-actions <>

Author: MaikuB

flutter_local_notifications/CHANGELOG.md

@@ -1,3 +1,7 @@
+# [15.0.1]
+
+* [Android] Fixed issue [2033](https://github.com/MaikuB/flutter_local_notifications/issues/2033) where notifications on scheduled using older version of the plugin would fail to have the next subsequent ones scheduled. This issue started occuring in 14.0 where support for inexact notifications was added using the `ScheduleMode` enum that was added and resulted in the deprecation of `androidAllowWhileIdle`. A mechanism was added to help "migrate" old notifications that had `androidAllowWhileIdle` specified but didn't account for how there are recurring notifications that were scheduled using older versions of the plugin prior to `androidAllowWhile` being added
+
 # [15.0.0]
 
 * **Breaking change** removed deprecated `schedule()`, `showDailyAtTime()` and `showWeeklyAtDayAndTime()` methods. Notifications that were scheduled prior to this release should still work

flutter_local_notifications/android/src/main/java/com/dexterous/flutterlocalnotifications/FlutterLocalNotificationsPlugin.java

@@ -584,6 +584,13 @@ private static void scheduleNextRepeatingNotification(
     PendingIntent pendingIntent =
         getBroadcastPendingIntent(context, notificationDetails.id, notificationIntent);
     AlarmManager alarmManager = getAlarmManager(context);
+    if (notificationDetails.scheduleMode == null) {
+      // This is to account for notifications created in older versions prior to allowWhileIdle
+      // being added so the deserialiser.
+      // Reference to old behaviour:
+      // https://github.com/MaikuB/flutter_local_notifications/blob/4b723e750d1371206520b10a122a444c4bba7475/flutter_local_notifications/android/src/main/java/com/dexterous/flutterlocalnotifications/FlutterLocalNotificationsPlugin.java#L569C37-L569C37
+      notificationDetails.scheduleMode = ScheduleMode.exactAllowWhileIdle;
+    }
 
     setupAllowWhileIdleAlarm(
         notificationDetails, alarmManager, notificationTriggerTime, pendingIntent);

flutter_local_notifications/pubspec.yaml

@@ -2,7 +2,7 @@ name: flutter_local_notifications
 description: A cross platform plugin for displaying and scheduling local
   notifications for Flutter applications with the ability to customise for each
   platform.
-version: 15.0.0
+version: 15.0.1
 homepage: https://github.com/MaikuB/flutter_local_notifications/tree/master/flutter_local_notifications
 issue_tracker: https://github.com/MaikuB/flutter_local_notifications/issues