Generate GetSnapshot

[hogesako]

Description

Generate GetSnapshot
opensearch-project/opensearch-api-specification#606

Issues Resolved

GetSnapshot is just an example and may not be resolved.
#420

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[Xtansia]

This is great @hogesako, thank you for picking this up end-to-end! 🙌

This is somewhat tricky from the breaking change perspective, as it's technically breaking, but it is just removing things that were never supported by OpenSearch and were stopping making GetSnapshot requests, so is also really a fix.

If we're wanting to backport this to 2.x, this needs an entry added to the CHANGELOG, otherwise if it's just going in the eventual 3.x it should be documented in UPGRADING.

@reta Do you have any opinions or reservations about backporting this to 2.x?

[reta]

@reta Do you have any opinions or reservations about backporting this to 2.x?

@Xtansia I think everything looks fine except SnapshotInfo that changes quite a few data types. We probably could manually backport it in a backward compatible way, what do you think?

[hogesako]

@Xtansia
I have appended to CHANGELOG.
There is a data types change, is there any other work needed?

[hogesako]

@Xtansia
Will this PR be backported to 2.x?

[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 128

To backport manually, run these commands in your terminal:

# Navigate to the root of your repository
cd $(git rev-parse --show-toplevel)
# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/opensearch-java/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/opensearch-java/backport-2.x
# Create a new branch
git switch --create backport/backport-1299-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 1c7c6e065b22b4a275a335f13eb06aa17ec20a87
# Push it to GitHub
git push --set-upstream origin backport/backport-1299-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/opensearch-java/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-1299-to-2.x.

[Xtansia]

@hogesako It will need to be manually backported but tweaked to minimise breaking changes in 2.x