Change JDK baseline (v3)

[jodastephen]

Version 3 should be based off a new baseline JDK.

Java 11 is the first sensible version beyond the module system. As a general rule, Joda-Time has been conservative with the JDK version, thus Java 11 would be the natural baseline, but it is likely to EOL before Java 8.

Java 21 is the latest version, and likely to be more adopted than 11 or 17 over time. Users wanting jlink support will generally be pushing up to the latest LTS release, making this a reasonably strong choice.

Need to identify if there are any APIs or issues that push one way or the other between these versions.

Any thoughts welcome.

[silviuburceadev]

Spring Boot 3 requires Java 17 and many people are migrating to Java 17 just to be able to use SB 3. The adoption rate for Java 21 isn't great and forcing a minimum of Java 21 will not help the adoption rate of joda-time v3 either.

Java 21 is relatively new and the tooling is still catching up.

• PMD has just released v7.0.0 with Java 21 support: https://github.com/pmd/pmd/releases/tag/pmd_releases%2F7.0.0
• Sonar will release 10.5 sometime in April with Java 21 support: https://community.sonarsource.com/t/when-do-you-plan-to-support-the-java-21-lts-for-the-sonar-maven-plugin/102106/16 & https://community.sonarsource.com/t/sonar-community-roundup-february-17-february-23/109785

Hope this helps.

[jodastephen]

My plan is to move to a Java 21 baseline at some point.