Update bundled JDK to 21.0.12.1+1

[reta]

Description

Update bundled JDK to 21.0.12.1+1 (new JDK CPU release cadence).
See please https://www.oracle.com/security-alerts/cspuaug2026.html#AppendixJAVA

Related Issues

N/A

Check List

• Functionality includes testing.
• API changes companion pull request created, if applicable.
• Public documentation issue/PR created, if applicable.

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[github-actions]

PR Reviewer Guide 🔍

(Review updated until commit a9e9533)

Here are some key observations to aid the review process:

🧪 No relevant tests

🔒 No security concerns identified

✅ No TODO sections

🔀 No multiple PR themes

⚡ Recommended focus areas for review Regex Capture Group Shift The updated VERSION_PATTERN regex changed the minor version group from (\\.\\d+\\.\\d+)? to (\\.\\d+\\.\\d+(?:\\.\\d+)?)?. While this now matches versions like 21.0.12.1+1, callers relying on capture group indices to extract the build/hash portions still work because the added (?:...) is non-capturing. However, verify that any code parsing the version string (e.g., extracting the fourth component .1) handles the optional fourth segment correctly, as it is now bundled inside group 2 rather than being a separate group. Downstream consumers expecting a strict three-part version may misparse the new format. private static final Pattern VERSION_PATTERN = Pattern.compile( "(\\d+)(\\.\\d+\\.\\d+(?:\\.\\d+)?)?\\+(\\d+(?:\\.\\d+)?)(@([a-f0-9]{32}))?" );

[github-actions]

Persistent review updated to latest commit a9e9533

[github-actions]

❌ Gradle check result for a9e9533: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?