/**
  * Get default order by.
  *
  * @return array|null
  */
 protected function getDefaultOrderBy()
 {
     $ids = $this->metadata->getIdentifierFieldNames();
     $orderBy = $ids ? [] : null;
     foreach ($ids as $pk) {
         $orderBy[$pk] = 'ASC';
     }
     return $orderBy;
 }
 protected function generateConstant(ClassMetadataInfo $metadata)
 {
     return str_replace(array('<tableName>', '<key>'), array($metadata->getTableName(), implode(',', $metadata->getIdentifierFieldNames())), static::$constantsTemplate);
 }