title: Android studio: this project is not gradle based project
body: <p>I have one project which was initially in eclipse, then i managed somehow to convert it to gradle and everything was working fine in Android Studio.</p>
  
  <p>But then i didn't work some time with the project and after few months when i returned to project i am surprised that Android Studio has problems with this project.</p>
  
  <p>When i selected "Android" from top left dropdown in AS, where you should see the project as Android, i saw no files, then i did something and now i see there one empty folder Java.</p>
  
  <p>If i hit button "sync project with gradle files" AS says message as posted in name of question, but it is gradle based project.. there are gradle files etc.</p>
  
  <p>Do you someone know why is this problem? Why it should stop work like this?</p>
  
  <p>Thank you</p>