NotificationBuilderSample.kt

val notificationTrampolineActivityIntent =
        Intent(context.applicationContext, NotificationTrampolineActivity::class.java)
    // Create the TaskStackBuilder
    val resultPendingIntent: PendingIntent? = TaskStackBuilder.create(context).run {
        // Add the intent, which inflates the back stack
        addNextIntentWithParentStack(notificationTrampolineActivityIntent)
        // Get the PendingIntent containing the entire back stack
        getPendingIntent(0, PendingIntent.FLAG_UPDATE_CURRENT or
                // mutability flag required when targeting Android12 or higher 
                PendingIntent.FLAG_IMMUTABLE)

    val notification = NotificationCompat.Builder(context, NOTIFICATION_CHANNEL_ID)
        .setSmallIcon(R.mipmap.ic_launcher)
        .setContentTitle("Android12")
        .setContentText("Notification trampoline restrictions fix")
        .addAction(R.mipmap.ic_launcher, "Open activity", resultPendingIntent)
        .setAutoCancel(true)
        .build()

    notificationManager.notify(getUniqueId(), notification)