protected void versionTestConcurrentEventsOnEmptyRegion() {
    // create an empty region in vm0 and replicated regions in VM 1 and 3,
    // then perform concurrent ops
    // on the same key while creating the region in VM2. Afterward make
    // sure that all three regions are consistent

    final String name = getUniqueName() + "-CC";
    SerializableRunnable createRegion = new SerializableRunnable() {
      @Override
      public void run() {
        // set log-level to fine so we'll see InitialImageOperation keys in the log for
        // GEODE-6326
        System.setProperty(DistributionConfig.LOG_LEVEL_NAME, "info");
        final RegionFactory<?, ?> f;
        if (VM.getVMId() == 0) {
          f = getCache().createRegionFactory(
              getRegionAttributes(RegionShortcut.REPLICATE_PROXY.toString()));
        } else {
          if (VM.getVMId() == 2) {
            InitialImageOperation.slowImageProcessing = 1;
          }
          f = getCache().createRegionFactory(getRegionAttributes());
        }
        CCRegion = (LocalRegion) f.create(name);
      }
    };

    prepConcurrentEventsTest(name, createRegion);

    // For no-ack regions, messages may still be in flight between replicas at this point
    try {
      await("Wait for the members to eventually be consistent")
          .untilAsserted(() -> {
            // check consistency of the regions
            Map r1Contents = vm1.invoke(MultiVMRegionTestCase::getCCRegionContents);
            Map r2Contents = vm2.invoke(MultiVMRegionTestCase::getCCRegionContents);
            Map r3Contents = vm3.invoke(MultiVMRegionTestCase::getCCRegionContents);
            checkResults(r1Contents, r2Contents, r3Contents);
          });
    } finally {
      vm1.invoke("dump region contents", () -> CCRegion.dumpBackingMap());
      vm2.invoke("dump region contents", () -> {
        CCRegion.dumpBackingMap();
        InitialImageOperation.slowImageProcessing = 0;
      });
      vm3.invoke("dump region contents", () -> CCRegion.dumpBackingMap());
    }
  }
This tests the concurrency versioning system to ensure that event conflation happens correctly
and that the statistic is being updated properly
geode-dunit/src/main/java/org/apache/geode/cache30/MultiVMRegionTestCase.java