Avro went the opposite way to most and just makes the concept of an optional field implementable via a union with null Non union fields can even be upgraded t

Avro went the opposite way to most and just makes the concept of an optional field implementable via a union with null Non union fields can even be upgraded to unions later Personally I find the protobufs "everything is optional!" Behaviour fucking insane and awful to deal with, but it is true to the semantics of its underlying wire format.