Symfony\Component\DependencyInjection\ContainerBuilder::findDefinition PHP Method

    public function findDefinition($id)
    {
        $id = strtolower($id);

        while (isset($this->aliasDefinitions[$id])) {
            $id = (string) $this->aliasDefinitions[$id];
        }

        return $this->getDefinition($id);
    }

 /**
  * {@inheritdoc}
  */
 public function process(ContainerBuilder $container)
 {
     // loaders
     $loaders = array();
     $loadersReferences = array();
     foreach ($container->findTaggedServiceIds('translation.loader') as $id => $attributes) {
         $loaders[$id][] = $attributes[0]['alias'];
         $loadersReferences[$attributes[0]['alias']] = new Reference($id);
         if (isset($attributes[0]['legacy-alias'])) {
             $loaders[$id][] = $attributes[0]['legacy-alias'];
             $loadersReferences[$attributes[0]['legacy-alias']] = new Reference($id);
         }
     }
     if ($container->hasDefinition('lexik_translation.translator')) {
         $container->findDefinition('lexik_translation.translator')->replaceArgument(2, $loaders);
     }
     if ($container->hasDefinition('lexik_translation.importer.file')) {
         $container->findDefinition('lexik_translation.importer.file')->replaceArgument(0, $loadersReferences);
     }
     // exporters
     if ($container->hasDefinition('lexik_translation.exporter_collector')) {
         foreach ($container->findTaggedServiceIds('lexik_translation.exporter') as $id => $attributes) {
             $container->getDefinition('lexik_translation.exporter_collector')->addMethodCall('addExporter', array($id, new Reference($id)));
         }
     }
 }