"serialization code"? Maybe it's an issue with Java. In Rust if I add a new field, I just wrap it in an Option. When de-serialized, old objects have a None, n

"serialization code"? Maybe it's an issue with Java. In Rust if I add a new field, I just wrap it in an Option. When de-serialized, old objects have a None, new objects with the field have a Some. When serializing it's just `Some (5)` instead of `5`, if it's an int. No runtime crashes from nulls, either.