title: Youtube player support fragment no longer working on Android studio 3.2 (androidx)
body: <p>I just updated my Android Studio to version 3.2 and followed instructions to use androidx.</p>
  
  <p>I've been using a Youtube fragment inside a Fragment activity and everything worked perfectly but, after the update, these 3 simple lines now give me the error "Cannot resolve method 'add(...)'":</p>
  
  <pre><code>YouTubePlayerSupportFragment youTubePlayerFragment = YouTubePlayerSupportFragment.newInstance();
  FragmentTransaction transaction = getChildFragmentManager().beginTransaction();
  transaction.add(R.id.youtube_fragment, youTubePlayerFragment).commit();
  </code></pre>
  
  <p>...and when i try to use "replace" instead of "add" it says: "Wrong 2nd argument type. Found: 'com.google.android.youtube.player.YouTubePlayerSupportFragment', required: 'androidx.fragment.app.Fragment'"</p>
  
  <p>...which makes me think that the problem has to do with the new AndroidX feature.</p>
  
  <p>The problem is that the add method wants the second parameter of type:</p>
  
  <pre><code>androidx.fragment.app.Fragment
  </code></pre>
  
  <p>...but the YouTubePlayerSupportFragment returns a:</p>
  
  <pre><code>android.support.v4.app.Fragment
  </code></pre>
  
  <p>Does anyone know how to solve this problem?
  Is there a way to cast the "android.support.v4.app.Fragment" into the "androidx.fragment.app.Fragment"?</p>