class MergeExtensionConfigurationPass

1. 8.x drupal/core/vendor/symfony/http-kernel/Symfony/Component/HttpKernel/DependencyInjection/MergeExtensionConfigurationPass.php \Symfony\Component\HttpKernel\DependencyInjection\MergeExtensionConfigurationPass
2. 8.x drupal/core/vendor/symfony/dependency-injection/Symfony/Component/DependencyInjection/Compiler/MergeExtensionConfigurationPass.php \Symfony\Component\DependencyInjection\Compiler\MergeExtensionConfigurationPass

Kernel.php in drupal/core/vendor/symfony/http-kernel/Symfony/Component/HttpKernel/Kernel.php

MergeExtensionConfigurationPassTest.php in drupal/core/vendor/symfony/http-kernel/Symfony/Component/HttpKernel/Tests/DependencyInjection/MergeExtensionConfigurationPassTest.php

class MergeExtensionConfigurationPass extends BaseMergeExtensionConfigurationPass {
  private $extensions;
  public function __construct(array $extensions) {
    $this->extensions = $extensions;
  }
  public function process(ContainerBuilder $container) {
    foreach ($this->extensions as $extension) {
      if (!count($container
        ->getExtensionConfig($extension))) {
        $container
          ->loadFromExtension($extension, array());
      }
    }
    parent::process($container);
  }

}