@Override
      public void beforeSendMessage(ClusterDistributionManager dm, DistributionMessage message) {
        if (message instanceof PrepareBackupRequest) {
          DistributionMessageObserver.setInstance(null);
          logger.info("#### After getting into observer to create regionName2 in vm1");
          getBlackboard().signalGate("createRegion");
          logger.info("#### After signalling create region");
          try {
            getBlackboard().waitForGate("createdRegion", 30, SECONDS);
          } catch (InterruptedException | TimeoutException ex) {
            throw new RuntimeException("never was notified region was created", ex);
          }
        }
      }
Test what happens when we restart persistent members while there is an accessor concurrently
performing puts.
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/backup/BackupDistributedTest.java