KAFKA-14691; [1/N] Add new fields to OffsetFetchRequest and OffsetFetchResponse - WIP

[clolov]

This is part 1 of KAFKA-14691. I change the JSON files which are used to generate the POJOs used during requests and responses.

[Hangleton]

Thanks @clolov for the PR. Also tagging @jolshan who had started to look at the same a while ago.

[Hangleton]

nit: The "about" field could be on a new line.

[Hangleton]

Do we want to add these fields in this PR?

[jolshan]

Since this is still under development, can we set the flag to indicate the latest version is unstable?

[dajac]

I have a few comments/questions:

• I am not really comfortable with merging this without the server side implementation. @clolov Is there a strong reason to not do them together?
• I agree with @Hangleton that it may be better to start with adding the TopicId only. This is complicated enough on its own. We can the other fields afterwards.
• I agree with @jolshan that we should set "latestVersionUnstable": true while in development.

[clolov]

I have a few comments/questions:

1. I am not really comfortable with merging this without the server side implementation. @clolov Is there a strong reason to not do them together?

2. I agree with @Hangleton that it may be better to start with adding the TopicId only. This is complicated enough on its own. We can the other fields afterwards.

3. I agree with @jolshan that we should set `"latestVersionUnstable": true` while in development.

I will accommodate 2 and 3 in subsequent commits. There was no reason for 1 other than splitting the pull request into nicer to review chunks. I am happy with trying to put Request/Respone changes + server side changes + tests in the same pull request similar to #13240.

Thank you all for the reviews!

[dajac]

Closing this PR for now as the topic id work will be done later. We can re-open it when we resume the work.