Other than the release notes, if you login to the BCM Download area in BCM Support and go to where you can get Spectrum, the release of Kafka will be available as a downloadable tarball. You can get the version of Kafka from the version of name of the tarball file. If there is no Kafka tarball there then go to the previous Spectrum release and check (since they may not update Kafka with every new release of NetOps).