title: Can't resolve Android databinding class
body: <p>While using data binding , I am not able to get class <code>MainActivityBinding</code>  as per <a href="https://developer.android.com/tools/data-binding/guide.html" rel="noreferrer">Data Binding Guide</a></p>
  
  <p>My layout name is <code>activity_main.xml</code>.
  I am also see <a href="https://stackoverflow.com/questions/31365692/android-databinding-how-and-when-the-binding-classes-will-be-generated">Android - DataBinding - How and when the Binding classes will be generated?</a> but it can't help me.</p>