case class MyCaseClass(name: String, enabled: Boolean)

case class Parent(parentName: String,
                  collection: Map[String, MyCaseClass])

Parent(
    "parent-name",
    Map(
        "external-name-a", MyCaseClass("internal-name-a", true),
        "external-name-b", MyCaseClass("internal-name-b", false)
    )
 )

Seq[name = <map key>, enabled = <boolean value from MyCaseClass>]

{ ...
      collection: [
      {
        name: "external-name-a",
        enabled: true
      },
      {
        name: "external-name-a",
        enabled: false
      }
    ]
  ...
  }

object Parent {

  implicit val encodeParent: Encoder[Parent] = (parent: Parent) => {
    Json.obj(
      ("name", parent.name.asJson),
      ("collection", parent.collection.asJson),
    )
  }

  implicit val encodeCollection: Encoder[Map[String, MyCaseClass]] = (measurements: Map[String, MyCaseClass]) => {

    //measurements.map
  }
}