Translate Validation Messages in Silex

app.php

<?php

$app->register(new Silex\Provider\TranslationServiceProvider(), array(
  'locale' => 'sr_Latn',
  'translation.class_path' => __DIR__ . '/../vendor/symfony/src',
  'translator.messages' => array()
));
$app['translator']->addLoader('xlf', new Symfony\Component\Translation\Loader\XliffFileLoader());
$app['translator']->addResource('xlf', __DIR__ . '/../vendor/symfony/src/Symfony/Bundle/FrameworkBundle/Resources/translations/validators.sr_Latn.xlf', 'sr_Latn', 'validators');