Serialize and deserialize a map with a case class key

uPickleRules.scala

//   "com.lihaoyi"            %% "upickle"                 % "0.7.5",

import upickle.default.{read,write}
import upickle.default.{ReadWriter => RW, macroRW}

object PickleMap {

    case class KeyClass(s: String, i: Int)
    object KeyClass{
        implicit val rw: RW[KeyClass] = macroRW
      }

    val m = Map[KeyClass, String](KeyClass("test 1", 17) -> "data 1", 
                                    KeyClass("test 2", 21) -> "data 1")

    def main(args : Array[String]) : Unit = {

        // convert to Json

        val serialized = write(m)

        println(s"Json output $serialized")

        // convert back

        val parsed = read[Map[KeyClass, String]](serialized)

        println(s"Parsed $parsed")
    }    
}