> Make all fields in a message required. This makes messages product types. Now you lost one of the biggest benefits of using protobufs, the possibility to mak

> Make all fields in a message required. This makes messages product types. Now you lost one of the biggest benefits of using protobufs, the possibility to make things backwards/forwards compatible. When you add a field to the proto, a server using the new version of the proto will fail to deserialize a request from a client using an older version that's missing that field. The author mentions this later, but doesn't really address it/propose a better solution, as far as I can see.