def flattenJsObject(obj: JsObject): JsObject = {
  val newObj = obj.fields.map {
    case (name, value) =>
      value match {
        case o: JsObject =>
          Some((name, o))
        case _ => None
      }
  }.flatMap(o => o).foldLeft(obj) {
    case (prev, next) =>
      JsObject(prev.fields.filterNot { case (name, value) => name == next._1 }) ++ next._2
  }
  if (newObj.fields.exists { case (name, value) => value.isInstanceOf[JsObject] }) {
    flattenJsObject(newObj)
  } else {
    newObj
  }
}