title: How do I disable back navigation and remove the back arrow on a Fragment, using Android Jetpack's Navigation component?
body: <blockquote>
    <p>I am using Google's recommended single activity pattern with Android
    Jetpack's Navigation component.</p>
  </blockquote>
  
  <p>Fragment 1 is an authentication screen. After the user is authenticated and navigates to Fragment 2, I would like to make pressing of the Android back button close the app, and remove the back arrow in the app bar.</p>
  
  <p>I have found methods, like <code>onBackPressedDispatcher</code>, to add / remove functionality from the back press, but nothing that also removes the back arrow.</p>
  
  <p>I have also tried <code>app:popUpTo="@+id/firstFragment"</code> when navigating from Fragment 1 to Fragment 2, but that doesn't work either.</p>
  
  <p>This should be possible to specify with a single line of code. Still trying to find. Any tips?</p>