Symfony\Component\DependencyInjection\Reference::__toString PHP Method

    public function __toString()
    {
        return (string) $this->id;
    }

 private function addBroadcaster($broadcaster, array $attributes, Reference $reference, Definition $definition, ContainerBuilder $container)
 {
     $definition->addMethodCall('add', [$attributes['alias'], $broadcaster]);
     // Register an alias for each broadcaster
     if (!$container->hasDefinition('ekko.broadcaster.' . $attributes['alias'])) {
         $container->setAlias('ekko.broadcaster.' . $attributes['alias'], $reference->__toString());
     }
 }