Update to Protobuf 4.x

[neeme-praks-sympower]

Edit by @ejona86: Protobuf has resolved the incompatibility with protobuf-java 4.x. For current status, see my two comments starting at #11015 (comment)

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Is your feature request related to a problem?

I would like to use the latest released version of Protobuf (4.26.0) but I cannot as gRPC is still using the old version.

Describe the solution you'd like

Update Protobuf dependency and make it work with the new version.

Describe alternatives you've considered

I hoped that the update would be easy (just a version bump) so I tried doing it myself but it resulted in a compilation failure so I'll leave it to you to figure it out.

The failure:

> Task :grpc-protobuf:compileJava FAILED
grpc-java/protobuf/src/main/java/io/grpc/protobuf/StatusProto.java:38: error: cannot access GeneratedMessageV3
          ProtoLiteUtils.metadataMarshaller(com.google.rpc.Status.getDefaultInstance()));
                                                                 ^
  class file for com.google.protobuf.GeneratedMessageV3 not found
grpc-java/protobuf/src/main/java/io/grpc/protobuf/StatusProto.java:171: error: cannot access Builder
        .setCode(status.getCode().value());
        ^
  class file for com.google.protobuf.GeneratedMessageV3$Builder not found
2 errors

[ganadist]

https://protobuf.dev/news/2023-12-05

Also, I'm wondering how this protobuf changes will affect

• gRPC public API changes
• Compatibility with artifacts which were generated by old protobuf/gRPC compilers.

[ejona86]

The protobuf breakage is pretty serious and goes against wisdom like https://jlbp.dev/JLBP-7 . I don't see how the community can absorb it. googleapis libraries are hit even harder than we are, so I think we'd wait until they have an idea how to deal with this (otherwise they couldn't upgrade to newer grpc versions). I don't expect that to be too big of a problem for the community, as I think most protobuf-using projects will be in shock.

I'm in discussions with others, but I'd expect the process to figure this out to take months.

[augi]

After updating to Protobuf 4.26.0, we observe this issue:

java.lang.NoClassDefFoundError: com/google/protobuf/GeneratedMessageV3
	at java.base/java.lang.ClassLoader.defineClass1(Native Method)
	at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1017)
	at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:150)
	at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:862)
	at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:760)
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:681)
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:639)
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:525)
	at io.grpc.health.v1.HealthGrpc.getCheckMethod(HealthGrpc.java:38)
	at io.grpc.health.v1.HealthGrpc.getServiceDescriptor(HealthGrpc.java:413)
	at io.grpc.health.v1.HealthGrpc.bindService(HealthGrpc.java:350)
	at io.grpc.health.v1.HealthGrpc$HealthImplBase.bindService(HealthGrpc.java:169)

The announcement of the Protobuf release contains this: [Java] The base class for generated messages will be GeneratedMessage, not GeneratedMessageV3.

So I guess this has to be adjusted.

[suztomo]

@neeme-praks-sympower Does any library or dependency require you to upgrade Protobuf runtime version to 4.x?

[be-hase]

It seems that proto-google-common-protos, which grpc-protobuf depends on, is not yet ver4 compliant.
https://github.com/googleapis/sdk-platform-java/tree/main/java-common-protos