I don’t understand condition in content translation module [on hold]

Don’t understand condition in controller /core/modules/content_translation/src/Controller/ContentTranslationController.php, line 171

$  link = isset($  links->links[$  langcode]['url']) ? $  links->links[$  langcode] : ['url' => $  entity->urlInfo()]; 

Variable $ links was defined as link to array, but in condition it used like object. Why?