Doctrine\OXM\OXMException::entityManagerClosed PHP Method

    public static function entityManagerClosed()
    {
        return new self("The XmlEntityManager is closed");
    }

 /**
  * Throws an exception if the EntityManager is closed or currently not active.
  *
  * @throws OXMException If the EntityManager is closed.
  */
 private function errorIfClosed()
 {
     if ($this->closed) {
         throw OXMException::entityManagerClosed();
     }
 }