Immutability is still there. You get to choose whether you want it or not.
For when you actually want a nullable field, I think the idea is that it is easy to have a wrapper message (just like boxing in languages). Such wrappers could even be made standard and provided by protobuf.
For when you actually want a nullable field, I think the idea is that it is easy to have a wrapper message (just like boxing in languages). Such wrappers could even be made standard and provided by protobuf.