$entity_type_manager = \Drupal::service('entity_type.manager');
      $moderation_information = \Drupal::service('content_moderation.moderation_information');
      $validator = new PoNumberConstraintValidator($entity_type_manager, $moderation_information);
      $workflow = $moderation_information->getWorkflowForEntity($tmp);
      $workflow_plugin = $workflow->getTypePlugin();
      $states = $validator->getModerationStates($tmp, $workflow);
      $old_state = $states['original']->id();
      $new_state = $states['new']->id();
      $po_received_state = $workflow_plugin->getState(PoNumberConstraintValidator::TRANSITION_TO_PO_RECEIVED);