title: Navigation Architecture Component - DestinationFragmentArgs is not generated
body: <p>I have this in app gradle:</p>
  
  <pre><code>apply plugin: 'androidx.navigation.safeargs'
  
  implementation 'android.arch.navigation:navigation-fragment-ktx:1.0.0'
  implementation 'android.arch.navigation:navigation-ui-ktx:1.0.0'
  </code></pre>
  
  <p>and this in the project gradle:</p>
  
  <pre><code>classpath 'android.arch.navigation:navigation-safe-args-gradle-plugin:1.0.0'
  </code></pre>
  
  <p>the navigation graph:</p>
  
  <pre><code>&lt;navigation xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto"
      xmlns:tools="http://schemas.android.com/tools"
      android:id="@+id/navigation_graph"
      app:startDestination="@id/loginPhoneNumberFragment"&gt;
  
      &lt;fragment
          android:id="@+id/loginPhoneNumberFragment"
          android:name="...fragments.LoginPhoneNumberFragment"
          android:label="@string/login_activity_title"
          tools:layout="@layout/fragment_login_phone_number"&gt;
          &lt;action
              android:id="@+id/action_loginPhoneNumberFragment_to_loginCodeFragment"
              app:destination="@id/loginCodeFragment"&gt;
              &lt;argument
                  android:name="prefix"
                  app:argType="string" /&gt;
              &lt;argument
                  android:name="phone_number"
                  app:argType="string" /&gt;
          &lt;/action&gt;
      &lt;/fragment&gt;
  
      &lt;fragment
          android:id="@+id/loginCodeFragment"
          android:name="...LoginCodeFragment"
          android:label="@string/login_activity_title"
          tools:layout="@layout/fragment_login_code" /&gt;
  
  &lt;/navigation&gt;
  </code></pre>
  
  <p>LoginPhoneNumberFragment:</p>
  
  <pre><code>val action = LoginPhoneNumberFragmentDirections.actionLoginPhoneNumberFragmentToLoginCodeFragment(prefix, phoneNumber)
  view?.findNavController()?.navigate(action)
  </code></pre>
  
  <p>LoginCodeFragment:</p>
  
  <pre><code>override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
          super.onViewCreated(view, savedInstanceState)
  
          val prefix = LoginCodeFragmentArgs.fromBundle(arguments).prefix //LoginCodeFragmentArgs is not recognized
  
      }
  </code></pre>
  
  <p>In the LoginPhoneNumberFragment it creates the "LoginPhoneNumberFragmentDirections" class, but on the destination class, LoginCodeFragment, it doesn't recognize "LoginCodeFragmentArgs".</p>
  
  <p>Can someone please tell me what am I missing?
  (I cleaned and rebuilded, and tried Invalidate caches...)</p>