title: Kotlin iterable
body: <p>Given this class:</p>
  
  <pre><code>data class CSVRecord(private val columns: SortedSet&lt;CSVColumn&gt;) : Iterable&lt;String&gt; {
  
      override fun iterator(): Iterator&lt;String&gt; {
          return columns.map { it.value }.iterator()
      }
  }
  </code></pre>
  
  <p>spotbugs raises an error:</p>
  
  <blockquote>
    <p>[ERROR] Questionable cast from Collection to abstract class java.util.List in com.example.CSVRecord.iterator() [com.example.CSVRecord] At CSVRecord.kt:[line 15] BC_BAD_CAST_TO_ABSTRACT_COLLECTION</p>
  </blockquote>
  
  <p>Is this just because spotbugs doesn't support Kotlin, or is my implementation potentially invalid?</p>