title: Fragment backstack building with NavDeepLinkBuilder
body: <p>I have a single activity app, with three fragments, A, B, C. In the normal app flow, fragments are opened in sequence: A->B->C 
  I have a foreground service with a notification that when clicked, should open fragment C. I use Navigation Architecture Component, and add the destination to the notification as a deeplink:</p>
  
  <pre><code>NotificationCompat.Builder(context, NOTIFICATION_CHANNEL)
      ....
      .setContentIntent(NavDeepLinkBuilder(context)
          .setGraph(R.navigation.main_navigation)
          .setDestination(R.id.fragmentC)
          .setArguments(bundle)
          .createPendingIntent())
      .build()
  </code></pre>
  
  <p>The fragment backstack is not built. When I navigate back from fragment C, I immediately get to fragment A, not to B. 
  According to <a href="https://developer.android.com/guide/navigation/navigation-principles#deep-link" rel="noreferrer">Principles of navigation</a> the backstack shall be natural, but I cannot seem to be able to achieve that. 
  What am I missing here? 
  Thank you.</p>