Union types are very rare (scala, typescript are the notable ones I can think of that implement it), most other languages only have sum types (which includes ja

Union types are very rare (scala, typescript are the notable ones I can think of that implement it), most other languages only have sum types (which includes java as well, see sealed interface/classes), where you have to create each unique set of types you want to use separately, wrapping each option into a marker type basically.