How to pass active locale/lang to mail templates data

use Event; 
use App; 
use 
System\Classes\MailManager;

public function boot()
{
    Event::listen('mailer.beforeAddContent', function ($mailer, $message, $view, $data, $raw, $plain) {

            $data['_current_locale'] = !empty($data['_current_locale']) ? $data['_current_locale'] : App::getLocale();

            if (MailManager::instance()->addContentToMailer($message, $view, $data, $plain)) {
                // the caller who fired the event is expecting a FALSE response to halt the event
                return false;
            }

        }, 1);
    }