core-bundle/src/Resources/contao/controllers/BackendAlerts.php
public function run()
	{
		$objTemplate = new BackendTemplate('be_alerts');
		$objTemplate->theme = Backend::getTheme();
		$objTemplate->base = Environment::get('base');
		$objTemplate->language = $GLOBALS['TL_LANGUAGE'];
		$objTemplate->title = StringUtil::specialchars($GLOBALS['TL_LANG']['MSC']['systemMessages']);
		$objTemplate->host = Environment::get('host');
		$objTemplate->charset = Config::get('characterSet');
		$objTemplate->messages = Message::generateUnwrapped() . Backend::getSystemMessages();
		$objTemplate->noMessages = $GLOBALS['TL_LANG']['MSC']['noSystemMessages'];

		return $objTemplate->getResponse();
	}
public function run()
	{
		$objTemplate = new BackendTemplate('be_alerts');
		$objTemplate->theme = Backend::getTheme();
		$objTemplate->base = Environment::get('base');
		$objTemplate->language = $GLOBALS['TL_LANGUAGE'];
		$objTemplate->title = StringUtil::specialchars($GLOBALS['TL_LANG']['MSC']['systemMessages']);
		$objTemplate->host = Environment::get('host');
		$objTemplate->charset = Config::get('characterSet');
		$objTemplate->messages = Message::generateUnwrapped() . Backend::getSystemMessages();
		$objTemplate->noMessages = $GLOBALS['TL_LANG']['MSC']['noSystemMessages'];

		return $objTemplate->getResponse();
	}
Run the controller and parse the template

@return Response