@Override
            public void sleep(long ms) {
                toSleep[0] = !toSleep[0];
                if (toSleep[0])
                    super.sleep(ms);
            }
Modify sleep() to call super.sleep() every second call
in order to avoid the endless loop in the tick() calls to the MockScheduler listener
trogdor/src/test/java/org/apache/kafka/trogdor/agent/AgentTest.java