[java] Rename of java_names.h -> names.h causes downstream breakages

[jvolkman]

What version of protobuf and what language are you using?
Version: v3.21.0
Language: Java

google/protobuf/compiler/java/java_names.h was renamed to names.h in 40db3da. Ideally there'd be some forwarding header to ease this transition.

See discussion about grpc-java at grpc/grpc-java#9218

Edited by ejona86: Fixed the commit link to reference protobuf instead of grpc PR commit

[ejona86]

Changing the name is fine from our perspective; we don't need the old header long-term. But it would have been good if the first release that included the new name didn't also delete the old one. That is a flag-day that is guaranteed to cause breakages and prevent upgrades.

[deannagarcia]

I'm sorry this breaking change was unannounced and no transitions were available. The protobuf team is working harder to ensure that breaking changes are intentional and well publicized, and will now follow this policy.

Would forwarding headers still be helpful or has this issue been resolved?

[ejona86]

gRPC Java has preprocessor logic to fix the build starting in 1.47.0. Most people don't build the grpc java protoc plugin from source, so they aren't impacted either way. I expect this mainly impacted Bazel users. To upgrade to newer Protobuf, those Bazel users would also need to upgrade to newer gRPC.

At this point forwarding includes wouldn't hurt, but I don't know if it'd actually benefit someone.

[deannagarcia]

Ok I will go ahead and close this bug since I think it's likely people already did the necessary migrations.