Consumer tests occasionally fail the exception:
kafka.common.TopicExistsException: Topic "topic" already exists.
Recreated this failure with some additional logging and it turns out that the failure is because a few tests which create a topic named "topic" close their Kafka server, but not the producer. When the ephemeral port used by the closed Kafka server gets reused in another Kafka server in a subsequent test, the producer retries of the previous test cause "topic" to be recreated using auto-create in the new Kafka server of the subsequent test. This results in an error in the consumer tests occasionally when the topic is auto-created before the test attempts to create it.