public function removeOrphanPromotionFromSku(SKU $sku, int $nid) {
    $promotion_detach_item[] = ['target_id' => $nid];
    $sku_promotions = $sku->get('field_acm_sku_promotions')->getValue();
    $sku_promotions = array_udiff($sku_promotions, $promotion_detach_item, function ($array1, $array2) {
      return $array1['target_id'] - $array2['target_id'];
    });
    $sku->get('field_acm_sku_promotions')->setValue($sku_promotions);
    $sku->save();
    // Update Sku Translations.
    $translation_languages = $sku->getTranslationLanguages(TRUE);
    if (!empty($translation_languages)) {
      foreach ($translation_languages as $langcode => $language) {
        $sku_entity_translation = $sku->getTranslation($langcode);
        $sku_entity_translation->get('field_acm_sku_promotions')->setValue($sku_promotions);
        $sku_entity_translation->save();
      }
    }
  }