Symfony\Component\Form\FormConfiguration::setDefaultCsrfSecret PHP Method

    static public function setDefaultCsrfSecret($secret)
    {
        self::$defaultCsrfSecret = $secret;
    }

 /**
  * Boots the Bundle.
  */
 public function boot()
 {
     if ($this->container->has('error_handler')) {
         $this->container->get('error_handler');
     }
     if ($this->container->hasParameter('csrf_secret')) {
         FormConfiguration::setDefaultCsrfSecret($this->container->getParameter('csrf_secret'));
         FormConfiguration::enableDefaultCsrfProtection();
     }
 }