Description:
------------
Hi there,

Searching Google for "php type hints" leads me to https://www.php.net/manual/en/language.oop5.typehinting.php, which leads to https://www.php.net/manual/en/functions.arguments.php#functions.arguments.type-declaration, which does not document '?type' hints, and documents that nullable arguments should be specified by a 'type $var = NULL', which is an exception to soon-deprecated behavior (https://github.com/php/php-src/blob/master/UPGRADING#L148).
(In fact, that deprecation indicated that it was 'sometimes used' in 'older PHP versions', as though it isn't the only solution documented!)

(Also, searching the PHP web site for 'type hints' returns no relevant results)