title: databinding.ActivityMainBinding unable to be imported in Android project
body: <p>I have a working Android Studio project, also installed via USB on my smartphone, it's a simply basic calculator.
  Now I have to rewrite the code for a lesson I teach, but Android Studio denies this import</p>
  
  <pre><code>import [com.username.projectname].databinding.ActivityMainBinding;
  </code></pre>
  
  <p>The app uses dataBinding I have enabled in Module:app and resync everything.</p>
  
  <p>The old project works, the new one not, with the same code, cause of this import is refused.</p>