I think this is can be handled with Lombok using @Getter and @Setter annotations (https://projectlombok.org/features/GetterSetter). It is not exactly the same because you call generated methods instead using assignment syntax but I guess it's close enough - if you need some custom logic in the getter/setter then you remove the annotation and write your own implementation (I think Lombok might be smart enough to ignore the annotation if an appropriately named getter/setter is present).

Non-nullable types sound great, I wonder if this could be introduced to Java in a backwards-compatible way (I suppose it would follow the same path with introducing explicitly nullable types first, though I guess it could be handled using Optionals?).