title: How can I target kotlin `internal` classes with proguard?
body: <p>I'd like to proguard (obfuscate) any classes marked with the kotlin <a href="https://kotlinlang.org/docs/reference/visibility-modifiers.html#classes-and-interfaces" rel="noreferrer"><code>internal</code></a> visibility modifier.</p>
  
  <p>Kotlin <code>internal</code> classes are public on the JVM, so they are visible and usable from Java source. I don't want these classes to be used or appear in autocomplete, so I would like to obsfuscate them to discourage their use.</p>
  
  <p>What proguard rule can I apply to target <code>internal</code> classes?</p>