title: How to select alternative sources for current API in Android Studio
body: <p>I am currently trying Android-R previews SDK on Android Studio, which does not have available SDK sources released yet. Unlike the "class not matching source" case, which will have an "alternative source available for class...", I don't find this option in my case. Please refer to the screenshot below.</p>
  
  <p>As most of the classes (interfaces) will still remain almost same as they are on the API level 29 SDK, which I have already installed and have sources downloaded. How can I tell Android Studio to use another source when it cannot find one to match the version?</p>
  
  <p>Thanks a lot.</p>
  
  <p><a href="https://i.stack.imgur.com/xYSA2.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/xYSA2.jpg" alt="AndroidStudio Source Not Available"></a></p>