private static void verifyNullCUMReference(Integer port) {
    Region<Object, Object> region =
        cache.getRegion(SEPARATOR + CacheServerImpl.generateNameForClientMsgsRegion(port));
    assertThat(region).isNotNull();

    Object[] arr = region.keySet().toArray();
    for (Object o : arr) {
      assertThat(((HAEventWrapper) o).getClientUpdateMessage()).isNull();
    }

  }
This test verifies that the memory footprint of the ha region queues is less when ha-overflow
is enabled (with an appropriate value of haCapacity) compared to when it is disabled, for the
same amount of data feed.
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/ha/HARQueueNewImplDistributedTest.java