Add success message to ZfcUser without modifying the ZfcUser code in any way

Module.php

<?php
namespace Application;

use Zend\Mvc\ModuleRouteListener;
use Zend\Mvc\MvcEvent;

class Module {
  public function onBootstrap(MvcEvent $e)
  {
    $eventManager        = $e->getApplication()->getEventManager();
    $serviceManager = $e->getApplication()->getServiceManager(); // Get the ServiceManager
    $viewHelperManager = $serviceManager->get('ViewHelperManager'); // This is how we will access the FlashMessenger view helper

    $moduleRouteListener = new ModuleRouteListener();
    $moduleRouteListener->attach($eventManager);

    $events = $eventManager->getSharedManager();
    
    $events->attach(
        'ZfcUser\Authentication\Adapter\AdapterChain', // Plugin to the Authentication chain event manager
        'authenticate', // and hook into the authentication event
        function ($e) use ($viewHelperManager) { // pass in the ViewHelperManager
            /* @var $messenger \Zend\View\Helper\FlashMessenger */
            $messenger = $viewHelperManager->get('flashmessenger'); // Get the flashmessenger view helper
            $messenger->getPluginFlashMessenger()->addSuccessMessage("Successfully Logged In!"); // Add the success message
        }
    );
  }
}