This is from the people who make mandatory protobuf fields "optional".
I just fundamentally disagree with Google on how to evolve data structures. Sloppy open-domain protobuf field presence, enum values, whatever are illusory extension points. Better to have discrete versions of a data structure --- Foo1, Foo2, Foo3, etc., and rigid checking in each one than to have just one "Foo" with optional-everything that changes implicitly over time.
I just fundamentally disagree with Google on how to evolve data structures. Sloppy open-domain protobuf field presence, enum values, whatever are illusory extension points. Better to have discrete versions of a data structure --- Foo1, Foo2, Foo3, etc., and rigid checking in each one than to have just one "Foo" with optional-everything that changes implicitly over time.