case class Id(number: Long, string: String)

import io.circe.generic.auto._
import io.circe.syntax._

class CirceSample {

  val mapStringToId = Map("str" -> Id(200, "str200"))
  val mapIdToId = Map(Id(100l, "str100") -> Id(200, "str200"))

  val jsonString1 = mapStringToId.asJson.spaces2
  val jsonString2 = mapIdToId.asJson.spaces2
}