code: public function getFilterOptions($idList, $usedOnly, &$arrCount = null)
      {
          if (!$this->getTagSource() && $this->getIdColumn()) {
              return [];
          }
  
          $return    = [];
          $idColName = $this->getIdColumn();
  
          // Fetch the value ids.
          $valueIds = $this->getValueIds($idList, $usedOnly, $arrCount);
          if (!\count($valueIds)) {
              return $return;
          }
  
          $valueColName = $this->getValueColumn();
          $aliasColName = $this->getAliasColumn();
  
          // Now for the retrieval, first with the real language.
          $values               = $this->getValues($valueIds, $this->getMetaModel()->getActiveLanguage());
          $arrValueIdsRetrieved = [];
          while ($row = $values->fetch(\PDO::FETCH_OBJ)) {
              $arrValueIdsRetrieved[]      = $row->$idColName;
              $return[$row->$aliasColName] = $row->$valueColName;
          }
          // Determine missing ids.
          $valueIds = array_diff($valueIds, $arrValueIdsRetrieved);
          // If there are missing ids and the fallback language is different than the current language, then fetch
          // those now.
          if ($valueIds
              && ($this->getMetaModel()->getFallbackLanguage() !== $this->getMetaModel()->getActiveLanguage())) {
              $values = $this->getValues($valueIds, $this->getMetaModel()->getFallbackLanguage());
              while ($row = $values->fetch(\PDO::FETCH_OBJ)) {
                  $return[$row->$aliasColName] = $row->$valueColName;
              }
          }
  
          return $return;
      }
docs: {@inheritDoc}