code:   public void injectChaos(Random random) throws Exception {
  
      // sometimes we restart one of the jetty nodes
      if (random.nextBoolean()) {
        JettySolrRunner jetty = jettys.get(random.nextInt(jettys.size()));
        ChaosMonkey.stop(jetty);
        log.info("============ Restarting jetty");
        ChaosMonkey.start(jetty);
      }
  
      // sometimes we restart zookeeper
      if (random.nextBoolean()) {
        zkServer.shutdown();
        log.info("============ Restarting zookeeper");
        zkServer = new ZkTestServer(zkServer.getZkDir(), zkServer.getPort());
        zkServer.run();
      }
  
      // sometimes we cause a connection loss - sometimes it will hit the overseer
      if (random.nextBoolean()) {
        JettySolrRunner jetty = jettys.get(random.nextInt(jettys.size()));
        ChaosMonkey.causeConnectionLoss(jetty);
      }
    }
  