This is a combination of two issues:
- the internal property `next.module.concurrency` is computed from `concurrency` when it should be computed from `consumer.concurrency`
- even if `next.module.concurrency` is set, the KafkaMessageBus rejects it, since it's not set in SUPPORTED_CONSUMER_PROPERTIES
As a result, the value used in partition calculation is always 1.
A workaround exists, by setting the `module.[moduleName].producer.minPartitionCount` property to the expected total value.