title: Flutter application with android fails to capture callback url
body: <p>I am trying to authenticate a flutter application against Spotify.
  For this, I use the <code>flutter_web_auth</code> package. I have a button to authenticate against Spotify.
  Once user clicks the button, the following function operates:</p>
  <pre><code>onPressed: () async {
    final spotifyAuthURL = Uri.https(
      'accounts.spotify.com',
      '/authorize',
      {
        'response_type': 'code',
        'client_id': dotenv.get('SPOTIFY_CLIENT_ID'),
        'redirect_uri':
            'https://vinyl_app_spotify.com/callback',
        'scope': 'user-read-private user-read-email',
      },
    );
  
    final result = await FlutterWebAuth.authenticate(
      url: spotifyAuthURL.toString(),
      callbackUrlScheme:
          'https://vinyl_app_spotify.com/callback',
    );
  },
  </code></pre>
  <p>I've also added the following activiy to the <code>AndroidManifest.xml</code> file as I should have done according to the <code>flutter_web_auth</code> package:</p>
  <pre><code>&lt;activity android:name=&quot;com.linusu.flutter_web_auth.CallbackActivity&quot; &gt;
      &lt;intent-filter android:label=&quot;flutter_web_auth&quot;&gt;
          &lt;action android:name=&quot;android.intent.action.VIEW&quot; /&gt;
          &lt;category android:name=&quot;android.intent.category.DEFAULT&quot; /&gt;
          &lt;category android:name=&quot;android.intent.category.BROWSABLE&quot; /&gt;
          &lt;data android:scheme=&quot;https://vinyl_app_spotify.com/callback&quot; /&gt;
      &lt;/intent-filter&gt;
  &lt;/activity&gt;
  </code></pre>
  <p>So after I click my application button, I do get access to Spotify, then the redirect url kicks in, but I just see this:
  <a href="https://i.stack.imgur.com/Ai2fs.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Ai2fs.png" alt="enter image description here" /></a></p>
  <p>So my android emulator could not capture the callback url.</p>
  <p>What is my mistake? Any advice..</p>