Expose params to toXContentChunked as well as per-chunk

[DaveCTurner]

Some responses change shape depending on the supplied params, and/or parse certain details out of params. By passing the params to toXContentChunked we can adjust the shape of the returned iterator and/or avoid duplicate parsing effort in ways that are not possible today where params is only made available to each leaf ToXContent object.

[elasticsearchmachine]

Pinging @elastic/es-core-infra (Team:Core/Infra)

[DaveCTurner]

TBH I think we could also pass in the builder once at the top level and then just have a Stream<Runnable> (maybe replacing Runnable with some more specific type for the context). Maybe that'd be too captureful? In any case this is enough for things like the cluster state API.

[rjernst]

LGTM

[rjernst]

Maybe that'd be too captureful? In any case this is enough for things like the cluster state API.

I would keep it simple. What you have already in this PR seems fine.

[original-brownbear]

TBH I think we could also pass in the builder once at the top level and then just have a Stream (maybe replacing Runnable with some more specific type for the context). Maybe that'd be too captureful?

Yea that's how I had it in the initial version of this and would still like to have it. Henning made me change it to what we have now ...

[original-brownbear]

I'm fine with this but I'd like the version where we just capture the params once even better if possible. We shouldn't have done it like we had in the first place lets go all the way to the correct solution IMO

[DaveCTurner]

Thanks both.

I missed the conversation about preferring to stick with the ToXContent API for the leaves - @henningandersen are you still sure we shouldn't use something simpler?

[henningandersen]

LGTM.

[henningandersen]

I missed the conversation about preferring to stick with the ToXContent API for the leaves - @henningandersen are you still sure we shouldn't use something simpler?

The primary problem I were trying to address was that each ChunkedToXContent had to do complicated state tracking, which this pattern avoided.

I am happy with the shape of this PR as is.