it seems to me that the --new-consumer option on the ConsoleConsumer is useless.
The useOldConsumer var is related to specify --zookeeper on the command line but then the ----bootstrap-server option (or the --new-consumer) can't be used.
If you use --bootstrap-server option then the new consumer is used automatically so no need for --new-consumer.
It turns out the using the old or new consumer is just related on using --zookeeper or --bootstrap-server option (which can't be used together, so I can't use new consumer connecting to zookeeper).
It's also clear when you use --zookeeper for the old consumer and the output from help says :
"Consider using the new consumer by passing [bootstrap-server] instead of [zookeeper]"
Before removing the --new-consumer option, this JIRA is for marking it as deprecated in the next release (then moving for a new release on removing such option).