class FileFormatterBase

abstract class FileFormatterBase extends EntityReferenceFormatterBase {
    
    /**
     * {@inheritdoc}
     */
    protected function needsEntityLoad(EntityReferenceItem $item) {
        return parent::needsEntityLoad($item) && $item->isDisplayed();
    }
    
    /**
     * {@inheritdoc}
     */
    protected function checkAccess(EntityInterface $entity) {
        // Only check access if the current file access control handler explicitly
        // opts in by implementing FileAccessFormatterControlHandlerInterface.
        $access_handler_class = $entity->getEntityType()
            ->getHandlerClass('access');
        if (is_subclass_of($access_handler_class, '\\Drupal\\file\\FileAccessFormatterControlHandlerInterface')) {
            return $entity->access('view', NULL, TRUE);
        }
        else {
            return AccessResult::allowed();
        }
    }

}