Support Protobuf v4

[mkaufmaner]

Feature or Problem Description

Currently, protouf v4 generated classes are not compatible with Apircurio libraries. Recent releases of libraries with protobuf dependencies like cel.dev and protovalidate use protobuf v4 and the Apicurio libraries fails to add them to the registry because protouf v4 is not compatible.

Proposed Solution

Upgrade to protobuf-java dependencies to v4.

Protobuf compatibility shims have been released in protobuf-java v4 for <=v3.x.x generated code built against v3.x.x prior to v4.26.0 breaking release.

Binary compatibility shims for GeneratedMessageV3, SingleFieldBuilderV3, RepeatedFieldBuilderV3, and their nested classes to restore binary compatibility with <=v3.x.x generated code built against v3.x.x prior to v4.26.0 breaking release. (protocolbuffers/protobuf@6bf01c5)

This will benefit the Apicurio by growing the user base since Confluent's schema registry does NOT support protobuf v4.

See https://docs.confluent.io/platform/current/schema-registry/fundamentals/serdes-develop/serdes-protobuf.html#limitations-and-developer-notes

The Confluent kafka-protobuf-serializer works with Google Protobuf v.3. Google Protobuf v.4 is currently not supported.

Additional Context

[apicurio-bot]

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