private void createCache(Properties props) {
    DistributedSystem ds = getSystem(props);
    assertNotNull(ds);
    ds.disconnect();
    ds = getSystem(props);
    cache = CacheFactory.create(ds);
    assertNotNull(cache);
  }
This is to test the serialization mechanism of ClientUpdateMessage. Added after CQ support.
This could be done in different way, by overflowing the HARegion queue.
geode-cq/src/distributedTest/java/org/apache/geode/internal/cache/ha/HADispatcherDistributedTest.java