code: private void createImageValidation(File imageFile) throws IOException {
      synchronized (imageValidatorLock) {
        InjectionHandler.processEvent(InjectionEvent.STANDBY_VALIDATE_CREATE);
        if (!running) {
          // fails the checkpoint
          InjectionHandler.processEvent(InjectionEvent.STANDBY_VALIDATE_CREATE_FAIL);
          throw new IOException("Standby: standby is quiescing");
        }
        imageValidator = new ImageValidator(imageFile);
        imageValidator.start();
      }
    }
docs: Creates image validation thread.
  @param imageFile
  @throws IOException on error, or when standby quiesce was invoked