old-new-wiaas/backend/app/plugins/wiaas/includes/admin/class-wiaas-admin-delivery-process.php

<?php

class Wiaas_Admin_Delivery_Process {

	public static function init() {
		require_once dirname( __FILE__ ) . '/delivery-process/class-wiaas-admin-delivery-process-flow.php';
		require_once dirname( __FILE__ ) . '/delivery-process/wiaas-admin-delivery-process-ajax.php';
	}
}

Wiaas_Admin_Delivery_Process::init();