Add support for edition 2023

[friscoMad]

I am unsure how to do that in this plugin, in grpc-java it was done in this commit

This is the error with 1.4.1:
XXX: is an editions file, but code generator protoc-gen-grpckt hasn't been updated to support editions yet. Please ask the owner of this code generator to add support or switch back to proto2/proto3

[ejona86]

grpc-java doesn't have support yet either. While the code can compile to support additions, the protobuf version actually used for the binaries on Maven Central is before editions was enabled. Since I don't see any C++ files for the generator in grpc-kotlin and I know it makes use of protoc-gen-grpc-java, I suspect your issue is actually the same as grpc/grpc-java#11526 (yes, I see you created this one first).

[ejona86]

Actually, it looks like the plugin needs to include the features supported in its response to protoc. The current code has some plumbing for that, but doesn't mention editions:

grpc-kotlin/compiler/src/main/java/io/grpc/kotlin/generator/protoc/CodeGenerators.kt

Lines 77 to 80 in a969a91

	try {
	builder.setSupportedFeatures(PluginProtos.CodeGeneratorResponse.Feature.FEATURE_PROTO3_OPTIONAL_VALUE.toLong())
	.addAllFile(build().map { toCodeGeneratorResponseFile(it) })
	} catch (failure: Exception) {

So I think you are right that grpc-kotlin needs an update here. But you're also blocked on the grpc-java bug.

[friscoMad]

@ejona86 You are right I was pretty sure that I was able to build a edition 2023 version of our services with the latest grpc-java but I have tried again and as reported it fails.
Still, adding support in grpc-kotlin should be easy, and it is a requirement anyway, so there is no reason for not making the change.