KAFKA-XXXXX: Improve consumer rebalance warning log with exception stack trace

[dhruvildave235]

What changed

Improved the consumer rebalance warning log by logging the full exception object instead of only the message.

Why

This improves observability and makes it easier to diagnose rebalance-related issues in production environments.

Testing

./gradlew :clients:compileJava

[dhruvildave235]

Thanks for the review!
The change is ready and CI has been validated locally.
Happy to address any feedback.

[Copilot]

Pull request overview

This PR improves observability in consumer rebalance error handling by logging the full exception object instead of just the exception message. This enables stack traces to be captured in logs, making it easier to diagnose rebalance-related issues in production environments.

Key changes:

• Modified the log.warn() call in ConsumerMembershipManager.consumerRebalanceListenerCallbackCompleted() to pass the exception object as the last parameter instead of e.getMessage()
• Updated the log message text from a more verbose description to a more concise format

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[dhruvildave235]

Thanks for the review.

I’ve fixed the indentation and updated the log message to follow Kafka’s positional placeholder style. The exception object is now passed to preserve stack traces.

Please let me know if anything else is needed.

[dhruvildave235]

Hi maintainers, just a gentle ping on this PR.
All CI checks have passed and the PR has CI approval.
Please let me know if any further changes are needed from my side.
Thanks!