title: Navigation Arch Component: Passing placeholder param for deeplink
body: <p>I am trying to implement a deeplink functionality using the new Navigation Component API v1.0.0-alpha05 but running into an issue.</p>
  
  <p>Using Android Studio 3.3 Canary 7</p>
  
  <p>Portion of my navigation_graph.xml</p>
  
  <pre><code>&lt;fragment
      android:id="@+id/noteDetailFragment"
      android:name="com.myapp.notes.notedetail.NoteDetailFragment"
      android:label="@string/label_note_detail"
      tools:layout="@layout/note_detail_fragment"&gt;
  
      &lt;argument
          android:name="noteId"
          android:defaultValue="0"
          app:argType="integer" /&gt;
  
      &lt;action
          android:id="@+id/action_noteDetail_to_editNote"
          app:destination="@id/editNoteFragment" /&gt;
  
      &lt;deepLink
          android:id="@+id/noteDetailDeepLink"
          app:uri="notesapp://notes/{noteId}" /&gt;
  &lt;/fragment&gt;
  </code></pre>
  
  <p>AndroidManifest.xml contains:</p>
  
  <pre><code>    &lt;activity android:name=".presentation.MainActivity"&gt;
          &lt;nav-graph android:value="@navigation/navigation_graph" /&gt;
          &lt;intent-filter&gt;
              &lt;action android:name="android.intent.action.MAIN" /&gt;
              &lt;category android:name="android.intent.category.LAUNCHER" /&gt;
          &lt;/intent-filter&gt;
      &lt;/activity&gt;
  </code></pre>
  
  <p>I am testing my deeplink with <code>adb shell am start -a android.intent.action.VIEW -d "notesapp://notes/2" com.myapp.notes</code></p>
  
  <p>The <code>noteId</code> is not present in either <code>NoteDetailFragmentArgs.fromBundle(arguments).noteId</code> or <code>arguments?.getInt("noteId", 0)</code> (a default value of <code>0</code> is returned in both cases)</p>
  
  <p>Printing out the Bundle shows that it is there:</p>
  
  <p><code>[{android-support-nav:controller:deepLinkIntent=Intent { act=android.intent.action.VIEW dat=notesapp://notes/2 flg=0x1000c000 pkg=com.mynotes.notes cmp=com.mynotes.notes.presentation.MainActivity }, noteId=2}]
  </code></p>
  
  <p>The same issue is observed if the deeplink uri is  <code>http://www.mynotes.com/notes/2</code></p>
  
  <p>How do I access the <code>noteId</code> when deeplinking? Thanks!</p>