class Impl : A, B {
  constructor(b: B) /* primary */ {
    super/*Any*/()
    /* <init>() */

  }

  override fun add(element: @FlexibleNullability String?): Boolean {
    return <this>.#<$$delegate_0>.add(element = element)
  }

  override fun addAll(elements: Collection<@FlexibleNullability String?>): Boolean {
    return <this>.#<$$delegate_0>.addAll(elements = elements)
  }

  override fun clear() {
    <this>.#<$$delegate_0>.clear()
  }

  override operator fun iterator(): MutableIterator<@FlexibleNullability String?> {
    return <this>.#<$$delegate_0>.iterator()
  }

  override fun remove(element: @FlexibleNullability String?): Boolean {
    return <this>.#<$$delegate_0>.remove(element = element)
  }

  override fun removeAll(elements: Collection<@FlexibleNullability String?>): Boolean {
    return <this>.#<$$delegate_0>.removeAll(elements = elements)
  }

  override fun retainAll(elements: Collection<@FlexibleNullability String?>): Boolean {
    return <this>.#<$$delegate_0>.retainAll(elements = elements)
  }

  override operator fun contains(element: @FlexibleNullability String?): Boolean {
    return <this>.#<$$delegate_0>.contains(element = element)
  }

  override fun containsAll(elements: Collection<@FlexibleNullability String?>): Boolean {
    return <this>.#<$$delegate_0>.containsAll(elements = elements)
  }

  override fun isEmpty(): Boolean {
    return <this>.#<$$delegate_0>.isEmpty()
  }

  override val size: Int
    override get(): Int {
      return <this>.#<$$delegate_0>.<get-size>()
    }

  local /* final field */ val <$$delegate_0>: B = b

}

fun box(): String {
  return "OK"
}