[Dubbo-3829] support google pb generic invocation

[vio-lin]

What is the purpose of the change

Currently, Generic Reference cannot support Google Protobuf. With bride usage of Google PB, we are going to support it via Generic Reference. See issue #3829

Brief changelog

1. add ProtobufUtils.class to serialize /deserialize Google Protobuf Object
2. modify GenericFilter.class and ProtocolUtils.class

feedback wanted

To support Google PB Testing, GenericFilter is part of my change, also Service Metadata have to support that. If the solution is ok, i will continue on the Service Metadata part.

• Make sure there is a GITHUB_issue field for the change (usually before you start working on it). Trivial changes like typos do not require a GITHUB issue. Your pull request should address just this issue, without pulling in other changes - one PR resolves one issue.
• Format the pull request title like [Dubbo-XXX] Fix UnknownException when host config not exist #XXX. Each commit in the pull request should have a meaningful subject line and body.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Write necessary unit-test to verify your logic correction, more mock a little better when cross module dependency exist. If the new feature or significant change is committed, please remember to add integration-test in test module.
• Run mvn clean install -DskipTests=false & mvn clean test-compile failsafe:integration-test to make sure unit-test and integration-test pass.
• If this contribution is large, please follow the Software Donation Guide.

[beiwei30]

I revisit this change today. I am hesitate to introduce protobuf dependency in dubbo-rpc-api too. Is it possible to introduce protobuf serialization impl in 'dubbo-serialization' first, then use it in GenericFilter like this:

                if (ProtocolUtils.isJavaGenericSerialization(generic)) {
                    try {
                        UnsafeByteArrayOutputStream os = new UnsafeByteArrayOutputStream(512);
                        ExtensionLoader.getExtensionLoader(Serialization.class)
                                .getExtension(Constants.GENERIC_SERIALIZATION_NATIVE_JAVA)
                                .serialize(null, os).writeObject(result.getValue());

or does 'dubbo-protostuff-serialization' meet your needs?

[beiwei30]

pls. check comments. I think we should find protobuf's serializer then use it, instead of introducing a direct dependency to protobuf.

[beiwei30]

pls. also revert your change in dubbo-distrbution/pom.xml. It is unnecessary any longer.

[beiwei30]

LGTM now.

[beiwei30]

there's one CI failure:

[ERROR]   The project org.apache.dubbo:dubbo-serialization:2.7.2-SNAPSHOT (/home/travis/build/apache/incubator-dubbo/dubbo-serialization/pom.xml) has 1 error
[ERROR]     Child module /home/travis/build/apache/incubator-dubbo/dubbo-serialization/dubbo-serialization-protobuf-json of /home/travis/build/apache/incubator-dubbo/dubbo-serialization/pom.xml does not exist
[ERROR]

[chickenlj]

This is a quite dependent module, I think we can merge it to the main branch and keep improving it. I will give it a test once I get some time.