In response to @chandsir, Ì had to change:
def toMap: Map[String,Any] = JsonUtil.toMap(unMarshallMe)
to def toMapAny: Map[String,Any] = JsonUtil.toMap[Any](unMarshallMe)
def toMapAny: Map[String,Any] = JsonUtil.toMap[Any](unMarshallMe)
and val jeroenMap = jeroenJson.toMap to val jeroenMap = jeroenJson.toMapAny
val jeroenMap = jeroenJson.toMap
val jeroenMap = jeroenJson.toMapAny
And it worked.
In response to @chandsir, Ì had to change:
to
def toMapAny: Map[String,Any] = JsonUtil.toMap[Any](unMarshallMe)and
val jeroenMap = jeroenJson.toMapto
val jeroenMap = jeroenJson.toMapAnyAnd it worked.