[bercianor]

Summary

• Explicitly install Temurin Java 8 before Java 17 for Gradle toolchain discovery, retaining Java 17 as the Gradle runtime.
• Cover all 10 Gradle-running jobs across 9 workflows, including license checks and Gradle Plugin Portal publication; the existing JVM8 release job already provisions Java 8.
• Preserve build/publish commands, credentials and Java 8 compatibility.

Background

• GitHub announced an ubuntu-latest migration to Ubuntu 26.04 between October 19 and November 19, 2026: [Ubuntu] ubuntu-latest label will use Ubuntu 26.04 in November 2026 actions/runner-images#14748
• The Ubuntu 26.04 inventory omits Java 8; Ubuntu 24.04 still includes it. The failed job image was not accessible, so its exact migration is not confirmed.

Validation

• ./gradlew spotlessCheck: BUILD SUCCESSFUL locally.
• Independent per-job structural verification: PASS for all 10 Gradle-running jobs; existing configuration preserved.
• actionlint: no new diagnostics compared with HEAD/master. Existing obsolete-action diagnostics and release.yml workflow_dispatch.branches syntax error remain out of scope.
• git diff --check: PASS.
• Native reliability reviews approved and acknowledged for each work unit.
• Independent verification of the initial five-file slice was unavailable and explicitly waived; follow-up verification was available and passed.
• Latest hosted CI pending. Release/publish commands were not run locally.