private DistributionMessageObserver createTestHookToBackup(
      WhenToInvokeBackup backupInvocationTestHook) {
    switch (backupInvocationTestHook) {
      case BEFORE_SENDING_DESTROYREGIONMESSAGE:
        return createTestHookToBackupBeforeSendingDestroyRegionMessage(
            () -> vm2.invoke(this::backupMember));
      case BEFORE_PROCESSING_REPLYMESSAGE:
        return createTestHookToBackupBeforeProcessingReplyMessage(
            () -> vm2.invoke(this::backupMember));
      default:
        throw new RuntimeException("Invalid backupInvocationTestHook " + backupInvocationTestHook);
    }
  }
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