whmcsProxmoxCloud/app/Hooks/AdminAreaFooterOutput.php

<?php
/* * ********************************************************************
*  ProxmoxVPS Product developed. (26.03.19)
* *
*
*  CREATED BY MODULESGARDEN       ->       http://modulesgarden.com
*  CONTACT                        ->       contact@modulesgarden.com
*
*
* This software is furnished under a license and may be used and copied
* only  in  accordance  with  the  terms  of such  license and with the
* inclusion of the above copyright notice.  This software  or any other
* copies thereof may not be provided or otherwise made available to any
* other person.  No title to and  ownership of the  software is  hereby
* transferred.
*
*
* ******************************************************************** */

use ModulesGarden\Servers\ProxmoxCloudVps\Core\Hook\HookIntegrator;

$hookManager->register(
    function ($args)
    {
        $hookIntegrator = new HookIntegrator($args);

        /**
         * @var $toReturn is a HTML integration code (or null if no integration was made)
         * you can add your code to this var before returning its content,
         * do not overwrite this var!
         */
        $toReturn = $hookIntegrator->getHtmlCode();

        if ($toReturn)
        {
            return $toReturn;
        }
    },
    100
);