@Override
        public FaultHandler build(String name, boolean fatal, Runnable action) {
            if (fatal) {
                return fatalFaultHandler;
            } else {
                return nonFatalFaultHandler;
            }
        }
This class manages a future which is completed with the proper value for
controller.quorum.voters once the randomly assigned ports for all the controllers are
known.
core/src/test/java/kafka/testkit/KafkaClusterTestKit.java