• [Improvement] Introduce message.purged event to indicate that a message that was not delivered to Kafka was purged. This most of the time refers to messages that were part of a transaction and were not yet dispatched to Kafka. It always means, that given message was not delivered but in case of transactions it is expected. In case of non-transactional it usually means #purge usage or exceeding message.timeout.ms so librdkafka removes this message from its internal queue. Non-transactional producers do not use this and pipe purges to error.occurred.
• [Fix] Fix a case where message.acknowledged would not have caller key.
• [Fix] Fix a bug where critical errors (like IRB::Abort) would not abort the ongoing transaction.