title: Multi Feature Instant Apps can't be proguarded?
body: <p>By using Android Studio 3.0 Beta 5, using the default Project (Empty Activity) with Instant Apps on.</p>
  
  <p>To turn on Proguard, I just set all the Build.Gradle (app, base and feature) with</p>
  
  <pre><code>debug {
     minifyEnabled true
     proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
  }
  </code></pre>
  
  <p>When compile the App works fine. However when compile the Instant Apps, it error out.</p>
  
  <blockquote>
    <p>java.lang.RuntimeException: Unable to instantiate activity
    ComponentInfo{com.elyeproj.myapplication/com.elyeproj.myapplication.feature.MainActivity}:
    java.lang.ClassNotFoundException: could not find
    com.elyeproj.myapplication.feature.MainActivity in any atom class
    loader or parent class loader</p>
  </blockquote>
  
  <p>It seems like the proguard just doesn't check the dependencies across features. How could this be solved?</p>