如何在Scala中"覆盖"内部类？

class Outer {
  class Inner {
    def printMessage(): Unit = {
      println("Inner class")
    }
  }
}

class Subclass extends Outer {
  override class Inner {
    override def printMessage(): Unit = {
      println("Overridden Inner class")
    }
  }
}

val obj = new Subclass()
val inner = new obj.Inner()
inner.printMessage() // 输出 "Overridden Inner class"