File plesk.kolab_chat.inc.php of Package roundcubemail-selfcontained

<?php
    $config = array();

    if (file_exists(RCUBE_CONFIG_DIR .'/'. ($_SERVER['HTTP_HOST'] ?? "") .'/mattermost.inc.php')) {
        include_once(RCUBE_CONFIG_DIR .'/'. ($_SERVER['HTTP_HOST'] ?? "") .'/mattermost.inc.php');
    }