if we want eliminate anything related to protobuf-java-forma and support official protobuf-java-util, do we need ProtobufFormatSupport interface ?

Indeed we could simplify a bit by removing ProtobufFormatSupport, but I would still keep ProtobufJavaUtilSupport as is so that it's easy to compare to ProtobufHttpMessageConverter which we have to maintain in parallel.

I’m doing new commits so that you can see what I fixed, at the end I’ll collect in one commit.

This looks much better. Feel free to squash the commits, I'm only looking for the end result.

In terms of your other question about where to add the converter to, I'd say in AbstractMessageBrokerConfiguration and MessageBrokerBeanDefinitionParser (i.e. the Java and XML config).

@parviz-93 thanks so much for your contribution and following through with the changes! This is now merged in. I ended up making a few further changes, adding a sub-class of the protobuf converter (just like in spring-web) because if it all came in one converter, the JSON format support wouldn't be optional. As a consequence I also decided to pull out the automatic registration in Java and XML config.

Thank you very much for your help and advice.

This was quick. Thanks a lot