[KAFKA-15485] Support building with Java 21 (LTS release)

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.7.0
• Assignee: Ismael Juma
• Reporter: Divij Vaidya
• Created: 22/Sep/23 09:44
• Updated: 25/Sep/23 14:21
• Resolved: 25/Sep/23 14:21

Description

JDK-21 is the latest LTS release which reached GA on 19th Sept 2023. This ticket aims to upgrade JDK used by Kafka to JDK-21 (currently it's JDK20).

Thanks to proactive work done by ijuma earlier [1][2][3], I do not anticipate major hiccups while upgrading to JDK-21.

As part of this JIRA we want to:
1. Upgrade Kafka to JDK 21
2. Replace the CI build for JDK 20 with JDK 21 (similar to [3] below)
3. Update the README (see[4]) to mention Kafka's support for JDK-21

[1] https://github.com/apache/kafka/pull/13840
[2] https://github.com/apache/kafka/pull/13582
[3] https://github.com/apache/kafka/pull/12948 
[4] https://github.com/apache/kafka/pull/14061 

Issue Links

• relates to: KAFKA-15117 SslTransportLayerTest.testValidEndpointIdentificationCN fails with Java 20 & 21
• relates to: KAFKA-15492 Enable spotbugs when building with Java 21
• relates to: KAFKA-15493 Ensure system tests work with Java 21
• links to: GitHub Pull Request #14427
• links to: GitHub Pull Request #14431
• links to: GitHub Pull Request #14433