title: A shorter way to transform enumValues to a multi-value map
body: <p>New to Kotlin. I was thinking if there is a shorter way to write the following piece of code. It means to categorize enum values into a multi-value map.</p>
  
  <pre><code>fun androidPermissionsByCategory(): Map&lt;String, List&lt;String&gt;&gt; {
      val result = hashMapOf&lt;String, MutableList&lt;String&gt;&gt;()
      enumValues&lt;AndroidPermission&gt;().onEach {
          result.getOrPut(it.permissionGroup, { mutableListOf() }).add(it.value())
      }
      return result
  }
  </code></pre>
  
  <p>Suggestions?</p>