Does not handle nullable values

[headinthebox]

@serializable
data class Bar(
val x: Int,
val y: Int? = null,
val z: Int?
)

println(pprint(Bar(x = 3, z = null)).plainText)
==>
Bar(x = 3, null, null)

would expect

Bar(x = 3, z = null), or perhaps Bar(x = 3, y = null, z = null)