core-bundle/src/HttpKernel/ControllerResolver.php
public function getController(Request $request)
    {
        if ($request->attributes->has('_controller')) {
            $fragmentConfig = $this->registry->get($request->attributes->get('_controller'));

            if (null !== $fragmentConfig) {
                $request->attributes->set('_controller', $fragmentConfig->getController());
            }
        }

        return $this->resolver->getController($request);
    }
public function getController(Request $request)
    {
        if ($request->attributes->has('_controller')) {
            $fragmentConfig = $this->registry->get($request->attributes->get('_controller'));

            if (null !== $fragmentConfig) {
                $request->attributes->set('_controller', $fragmentConfig->getController());
            }
        }

        return $this->resolver->getController($request);
    }
{@inheritdoc}