No need to be public

Author: aurimasc

com.unity.mobile.notifications/Runtime/Android/Plugins/com/unity/androidnotifications/UnityNotificationManager.java

@@ -107,7 +107,7 @@ private void initialize(Activity activity, NotificationCallback notificationCall
         mBackgroundThread.start();
     }
 
-    public static synchronized UnityNotificationManager getNotificationManagerImpl(Context context) {
+    static synchronized UnityNotificationManager getNotificationManagerImpl(Context context) {
         if (mUnityNotificationManager == null) {
             mUnityNotificationManager = new UnityNotificationManager();
         }