nullableString

fun JsonModel?.nullableString(key: String? = null, default: JsonObjectDefaultSelector<String?>): JsonDelegateProperty<String?>
fun JsonModel?.nullableString(key: String? = null, default: String?): JsonDelegateProperty<String?>
fun JsonModel?.nullableString(key: String): JsonDelegateProperty<String?>
val JsonModel?.nullableString: JsonDelegateProperty<String?>