end-to-end example isn't working any longer

When following the instructions in the end-to-end example, the service registry fails to start up, apparently not being able to connect to Kafka.

Unfortunately, the component versions in this example are severely outdated, e.g. still using WildFly and Thorntail. I'm not quite sure how to proceed with this one, we may be best off to simply remove that example to begin with, as updating it will require a substantial amount of time which may not be worth it. I suppose all the parts of this example are covered by others, too.