I'm doing some initial exploration of kafka and the system tools. With the console producer and consumers running, I'd like to run the ConsumerOffsetChecker, but it requires a group parameter. I don't know what to put there. Is there a tool I can run to get a list of consumer groups? I see a hint in the quantifind KafkaOffsetMonitor tool  that this shouldn't be too difficult. But, is there something in the provided kafka/zk tools?