title: Cannot find JDK '<unknown>' for module 'appcompatV7'
body: <p>I have this error popping up. </p>
  
  <p><em><strong>Error:java: Cannot find JDK '' for module 'appcompatV7'</em></strong></p>
  
  <p>I cant work out why its happening, im using compatibility library and added it in the project structure. Selected it as "Library module" and added as module dependency. </p>
  
  <p>Its working fine on another project with exactly the same set up.</p>