code: protected function getOneQueryBuilder($alias = null, $indexBy = null)
      {
          return $this
              ->createQueryBuilder($alias, $indexBy)
              ->select(
                  $alias,
                  'customer',
                  'customer_group',
                  'invoice_address',
                  'delivery_address',
                  'shipment_method',
                  'currency'
              )
              ->leftJoin($alias . '.customer', 'customer')
              ->leftJoin($alias . '.customerGroup', 'customer_group')
              ->leftJoin($alias . '.invoiceAddress', 'invoice_address')
              ->leftJoin($alias . '.deliveryAddress', 'delivery_address')
              ->leftJoin($alias . '.shipmentMethod', 'shipment_method')
              ->leftJoin($alias . '.currency', 'currency')
              ->setMaxResults(1);
      }
docs: Returns the "find one result" query builder.
  
  @param string $alias
  @param string $indexBy
  
  @return \Doctrine\ORM\QueryBuilder