Cannot resolve symbol asJava : Intellij idea

问题:

I've been doing scala coding on intellij idea. All was well until I added this piece of code (copied from https://stackoverflow.com/a/32380463/444644 ) :

  def toJava(x: Any): Any = {
    import scala.collection.JavaConverters._
    x match {
      case y: scala.collection.MapLike[_, _, _] =>
        y.map { case (d, v) => toJava(d) -> toJava(v) } asJava
      case y: scala.collection.SetLike[_,_] =>
        y map { item: Any => toJava(item) } asJava
      case y: Iterable[_] =>
        y.map { item: Any => toJava(item) } asJava
      case y: Iterator[_] =>
        toJava(y.toIterable)
      case _ =>
        x
    }
  }

This results in two "error" highlights for the first two asJava calls above. But the code compiles and runs fine. How to fix it?