protected function create_container(array $extensions)
{
$container = new ContainerBuilder(new ParameterBag($this->get_core_parameters()));
$extensions_alias = array();
foreach ($extensions as $extension) {
$container->registerExtension($extension);
$extensions_alias[] = $extension->getAlias();
}
$container->getCompilerPassConfig()->setMergePass(new MergeExtensionConfigurationPass($extensions_alias));
return $container;
}