KAFKA-19761 Gradle Shadow plugin version upgrade: 8.3.9 -->> 9.3.0

[dejan2609]

Prologue: https://github.com/apache/kafka/pull/19513#discussion_r2365708218

Release notes for Shadow plugin:

• https://gradleup.com/shadow/changes/#930-2025-12-05

I did some testing, and results look just fine :white_check_mark::

• gradle builds ./gradlew :jmh-benchmarks:shadowJar and ./gradlew releaseTarGz are successful
• generated distributions (kafka_2.13-4.2.0-SNAPSHOT-site-docs.tgz and and kafka_2.13-4.2.0-SNAPSHOT.tgz) have identical file numbers (for trunk and this branch)
• Kafka cluster starts and messages can be produced and consumed: https://kafka.apache.org/quickstart

:warning: disclaimer notes:

• solution is generated via Gemini CLI
• Gemini prompt is based on Jira ticket (previously created by me): KAFKA-19761

[dejan2609]

@chia7712 Please review when you have some time.

[dejan2609]

I'll rebase this onto trunk (to include a new, updated Gradle version into this branch/PR).

[dejan2609]

Hi @apoorvmittal10,

Can you please allocate some time to provide a review ?

[dejan2609]

Few tests are flaky/failing:

[dejan2609]

Gradle task that ends up with one failed test works as expected on my machine:

dejan@dejan-HP-ProBook-450-G7:~/kafka$ date
Sat 13 Dec 16:21:53 CET 2025
dejan@dejan-HP-ProBook-450-G7:~/kafka$ java -version 
openjdk version "17.0.17" 2025-10-21
OpenJDK Runtime Environment Temurin-17.0.17+10 (build 17.0.17+10)
OpenJDK 64-Bit Server VM Temurin-17.0.17+10 (build 17.0.17+10, mixed mode, sharing)
dejan@dejan-HP-ProBook-450-G7:~/kafka$ ./gradlew :streams:upgrade-system-tests-24:test -q
Starting build with version 4.3.0-SNAPSHOT (commit id 4196380b) using Gradle 9.2.1, Java 17 and Scala 2.13.18
Build properties: ignoreFailures=false, maxParallelForks=8, maxScalacThreads=8, maxTestRetries=0
dejan@dejan-HP-ProBook-450-G7:~/kafka$ date
Sat 13 Dec 16:22:18 CET 2025
dejan@dejan-HP-ProBook-450-G7:~/kafka$

:bulb: I will try to execute entire test suite on Github Action CI server once more.

[dejan2609]

All tests are fine now :white_check_mark:

@chia7712 can you allocate some time to review this one ?