protected function configureForm($form, AbstractOptions $options)
    {
        if (!$options instanceof ModuleOptions) {
            throw new \InvalidArgumentException(sprintf('$options must be instance of %s', ModuleOptions::class));
        }
        
        $size = $options->getAttachmentsMaxSize();
        $type = $options->getAttachmentsMimeType();
        $count = $options->getAttachmentsCount();

        $form->setIsDisableCapable(false)
             ->setIsDisableElementsCapable(false)
             ->setIsDescriptionsEnabled(true)
             ->setDescription(
                /*@translate*/ 'Attach images or PDF Documents to your CV. Drag&drop them, or click into the attachement area. You can upload up to %sMB',
                 [round($size/(1024*1024))>0? round($size/(1024*1024)):round($size/(1024*1024), 1)]
             )
             ->setParam('return', 'file-uri')
             ->setLabel(/*@translate*/ 'Attachments');

        /* @var $file \Core\Form\Element\FileUpload */
        $file = $form->get($this->fileName);

        $file->setMaxSize($size);
        if ($type) {
            $file->setAllowedTypes($type);
        }
        $file->setMaxFileCount($count);

        // pass form to element. Needed for file count validation
        // I did not find another (better) way.
        $file->setForm($form);
    }