1. Redundant types are not allowed
2. False as a standalone type is allowed only in php8.2, but I'm using LevelSetList::UP_TO_PHP_81

@@ @@
* @param bool|FALSE $user_id
* @return array
*/

• public function build_acl(bool $user_id = FALSE)

• public function build_acl(bool|false $user_id = FALSE)

Applied rules:

• UnionTypesRector