ext_localconf.php

<?php
defined('TYPO3') or die();

call_user_func(
    function()
    {

        \TYPO3\CMS\Extbase\Utility\ExtensionUtility::configurePlugin(
            'MdFullcalendar',
            'Cal',
            [
                \Mediadreams\MdFullcalendar\Controller\CalController::class => 'show, list, detail'
            ],
            // non-cacheable actions
            [
                \Mediadreams\MdFullcalendar\Controller\CalController::class => ''
            ]
        );

        // Will be used for the ajax calls
        \TYPO3\CMS\Extbase\Utility\ExtensionUtility::configurePlugin(
            'MdFullcalendar',
            'CalList',
            [
                \Mediadreams\MdFullcalendar\Controller\CalController::class => 'list'
            ],
            // non-cacheable actions
            [
                \Mediadreams\MdFullcalendar\Controller\CalController::class => ''
            ]
        );

        // Will be used for the ajax calls
        \TYPO3\CMS\Extbase\Utility\ExtensionUtility::configurePlugin(
            'MdFullcalendar',
            'CalDetail',
            [
                \Mediadreams\MdFullcalendar\Controller\CalController::class => 'detail'
            ],
            // non-cacheable actions
            [
                \Mediadreams\MdFullcalendar\Controller\CalController::class => ''
            ]
        );

        $iconRegistry = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance(\TYPO3\CMS\Core\Imaging\IconRegistry::class);
        
        $iconRegistry->registerIcon(
            'md_fullcalendar-plugin-cal',
            \TYPO3\CMS\Core\Imaging\IconProvider\SvgIconProvider::class,
            ['source' => 'EXT:md_fullcalendar/Resources/Public/Icons/PluginCal.svg']
        );
        
    }
);