Welcome to Scala 3.1.1 (18, Java OpenJDK 64-Bit Server VM).
Type in expressions for evaluation. Or try :help.

scala> object sun { val x = 42 }
// defined object sun

scala> import sun.x
-- [E008] Not Found Error: ---------------------------------------------------------------------------------------------
1 |import sun.x
  |           ^
  |           value x is not a member of sun
1 error found

scala> import jdk.CollectionConverters.*
-- [E008] Not Found Error: ---------------------------------------------------------------------------------------------
1 |import jdk.CollectionConverters.*
  |       ^^^^^^^^^^^^^^^^^^^^^^^^
  |       value CollectionConverters is not a member of jdk
1 error found

scala> import _root_.
<empty>                 dotty                   javax                   org                     sun
<special-ops>           images                  jdk                     repl                    toolbarButtonGraphics
com                     java                    netscape                scala                   xsbti

import scala.jdk.CollectionConverters._
// not in Scala 2/3
//import jdk.CollectionConverters._
// in Scala 2
//scalac -Yimports:java,scala,scala.Predef,scala.jdk hh.scala
//import CollectionConverters._

object HelloWorld {
  def main(args: Array[String]) = {
    val ss = java.util.List.of("Hello", "world")
    println(ss.asScala.mkString("", ", ", "!"))
  }
}

Welcome to Scala 2.13.8 (OpenJDK 64-Bit Server VM, Java 17.0.2).
Type in expressions for evaluation. Or try :help.

scala> object sun { val x = 42 }
object sun

scala> import sun.x
import sun.x

scala> import jdk.CollectionConverters._
                  ^
       error: object CollectionConverters is not a member of package jdk