(FR): Supports Java SDK 21 - 25

[luas10c]

Why can't we still support Java JDK 21 or even 25, since these are the stable LTS versions for a long time?

[luas10c]

Gradle 8 already has support for Java 21 and 25

[github-actions]

There hasn't been any activity on this issue in the past 3 months, so it has been marked as stale and it will be closed automatically if no further activity occurs in the next 7 days.