Data class primary constructor must have only property (val / var) parameters I am converting my Json into data object class: The JSON comes in this format: entry":[ { "im:name": {"label":"Growin' Up"} .... } So in my data class I have: data class Entry( val im:name: ImName ) But I am having an arror: Data class primary constructor must have only property (val / var) parameters I cant change the JSON returned