Set neural-search plugin 3.0.0 baseline JDK version to JDK-21

[reta]

Description

Set neural-search plugin 3.0.0 baseline JDK version to JDK-21

Issues Resolved

Closes #775

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Commits are signed as per the DCO using --signoff

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[reta]

@martin-gaievski fyi :-)

[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-2.x 2.x
# Navigate to the new working tree
cd .worktrees/backport-2.x
# Create a new branch
git switch --create backport/backport-838-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 68116603566107785c0439fa0599a044e4fddf8a
# Push it to GitHub
git push --set-upstream origin backport/backport-838-to-2.x
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-838-to-2.x.

[reta]

Thanks @martin-gaievski , please note - this is 3.x / main only, no backport is needed

[martin-gaievski]

understood, removing 'backport 2.x' label. Is the a plan to move 2.x to 21 at some point?

[reta]

Is the a plan to move 2.x to 21 at some point?

Not a baseline (== minimum required JDK version), as it would be breaking change