@Override
      public void beforeSendMessage(ClusterDistributionManager dm, DistributionMessage message) {
        if (message instanceof DLockRequestProcessor.DLockRequestMessage) {
          DistributionMessageObserver.setInstance(null);
          try {
            logger.info("#### before waiting for createdRegionAfterRecovery");
            getBlackboard().waitForGate("createdRegionAfterRecovery", 30, SECONDS);
            logger.info("#### after waiting for createdRegionAfterRecovery");
          } 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