CVE-2026-70907: OpenJDK: Enhance TLS server (bsc#1275764).
Non security issue fixed:
java-21-openjdk classlist depends on the CPU count of the build machine (bsc#1221224).
Changes for java-21-openjdk:
Update to jdk-21.0.12.1+1 (August 2026 CSPU)
backport upcoming upgrade of timezone data (bsc#1275035)
Explicitly use G1 if the JVM supports it. GC ergonomics pick
SerialGC on single-CPU machines. SerialGC does not support
dumping of the shared heap, thus the classlist is different on
a single-CPU builder.