Fix Android 5.1 and older not resuming app

App would not resume on Android 5 after the `taskAffinity=""` addition
added in the last commit. This seems to be an issue with
allowTaskReparenting not working in this case. Even explicitly enabling
 it did not work.

 `taskAffinity` is required for newer vesions of Android to correctly
 start a new task and to reparent it to the correct task. This is why
 two different implementations had to be added.

Author: jkasten2

OneSignalSDK/onesignal/src/main/AndroidManifest.xml

@@ -140,6 +140,12 @@
           android:theme="@android:style/Theme.Translucent.NoTitleBar"
           android:exported="true" />
 
+        <activity
+            android:name="com.onesignal.NotificationOpenedReceiverAndroid22AndOlder"
+            android:noHistory="true"
+            android:excludeFromRecents="true"
+            android:theme="@android:style/Theme.Translucent.NoTitleBar"
+            android:exported="true" />
     </application>
 
     <!-- NOTE: See release version for tags with placeholders -->

OneSignalSDK/onesignal/src/main/java/com/onesignal/GenerateNotificationOpenIntent.kt

@@ -10,26 +10,56 @@ class GenerateNotificationOpenIntent(
     private val startApp: Boolean
 ) {
 
-    private val notificationOpenedClass: Class<*> = NotificationOpenedReceiver::class.java
+    private val notificationOpenedClassAndroid23Plus: Class<*> = NotificationOpenedReceiver::class.java
+    private val notificationOpenedClassAndroid22AndOlder: Class<*> = NotificationOpenedReceiverAndroid22AndOlder::class.java
 
     fun getNewBaseIntent(
         notificationId: Int,
     ): Intent {
+        val intent =
+            if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.M)
+                getNewBaseIntentAndroidAPI23Plus()
+            else
+                getNewBaseIntentAndroidAPI22AndOlder()
+
+        return intent
+        .putExtra(
+            GenerateNotification.BUNDLE_KEY_ANDROID_NOTIFICATION_ID,
+            notificationId
+        )
         // We use SINGLE_TOP and CLEAR_TOP as we don't want more than one OneSignal invisible click
         //   tracking Activity instance around.
-        val intentFlags =
+        .addFlags(
             Intent.FLAG_ACTIVITY_SINGLE_TOP or
             Intent.FLAG_ACTIVITY_CLEAR_TOP
+        )
+    }
 
+    private fun getNewBaseIntentAndroidAPI23Plus(): Intent {
         return Intent(
             context,
-            notificationOpenedClass
+            notificationOpenedClassAndroid23Plus
         )
-        .putExtra(
-            GenerateNotification.BUNDLE_KEY_ANDROID_NOTIFICATION_ID,
-            notificationId
+    }
+
+    // See NotificationOpenedReceiverAndroid22AndOlder.java for details
+    private fun getNewBaseIntentAndroidAPI22AndOlder(): Intent {
+        val intent = Intent(
+            context,
+            notificationOpenedClassAndroid22AndOlder
         )
-        .addFlags(intentFlags)
+
+        if (getIntentVisible() == null) {
+            // If we don't show a visible Activity put OneSignal's invisible click tracking
+            // Activity on it's own task so it doesn't resume an existing one once it closes.
+            intent.addFlags(
+                Intent.FLAG_ACTIVITY_NEW_TASK or
+                Intent.FLAG_ACTIVITY_MULTIPLE_TASK or
+                Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET
+            )
+        }
+
+        return intent
     }
 
     /**

OneSignalSDK/onesignal/src/main/java/com/onesignal/NotificationOpenedReceiverAndroid22AndOlder.java

@@ -0,0 +1,60 @@
+/**
+ * Modified MIT License
+ *
+ * Copyright 2021 OneSignal
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * 1. The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * 2. All copies of substantial portions of the Software may only be used in connection
+ * with services provided by OneSignal.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package com.onesignal;
+
+import android.app.Activity;
+import android.content.Intent;
+import android.os.Bundle;
+
+/**
+ * This is the same as NotificationOpenedReceiver expect it doesn't contain
+ * android:taskAffinity="" in it's AndroidManifest.xml entry. This is to
+ * account for the resume behavior not working on Android API 22 and older.
+ *
+ * In Android 5.x and older, android:taskAffinity="" starts a new task as
+ * expected, however the allowTaskReparenting behavior does not happen which
+ * results in the app not resuming, when using reverse Activity trampoline.
+ * Oddly enough cold starts of the app were not a problem.
+ */
+public class NotificationOpenedReceiverAndroid22AndOlder extends Activity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        NotificationOpenedProcessor.processFromContext(this, getIntent());
+        finish();
+    }
+
+    @Override
+    protected void onNewIntent(Intent intent) {
+        super.onNewIntent(intent);
+        NotificationOpenedProcessor.processFromContext(this, getIntent());
+        finish();
+    }
+
+}

OneSignalSDK/unittest/src/test/java/com/test/onesignal/GenerateNotificationRunner.java

@@ -1180,7 +1180,7 @@ private void generateNotificationWithLaunchURL() throws Exception {
    }
 
    private void assertNotificationOpenedReceiver(@NonNull Intent intent) {
-      assertEquals("com.onesignal.NotificationOpenedReceiver", intent.getComponent().getClassName());
+      assertEquals(com.onesignal.NotificationOpenedReceiverAndroid22AndOlder.class.getName(), intent.getComponent().getClassName());
    }
 
    private void assertOpenMainActivityIntent(@NonNull Intent intent) {