private static void verifyNullValuesInCMR(final Integer port,
      String[] keys) {
    final Region<Object, Object> msgsRegion =
        cache.getRegion(generateNameForClientMsgsRegion(port));

    GeodeAwaitility.await().until(() -> msgsRegion.size() == 3);

    Set entries = msgsRegion.entrySet();
    Iterator iterator = entries.iterator();
    for (; iterator.hasNext();) {
      Entry entry = (Entry) iterator.next();
      ClientUpdateMessage cum = (ClientUpdateMessage) entry.getValue();
      for (String key : keys) {
        logger.debug("cum.key: " + cum.getKeyToConflate());
        // assert that the keys are not present in entries set
        assertThat(!key.equals(cum.getKeyToConflate())).isTrue();
      }
    }
  }
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