XF\Job\Manager::enqueueLater no longer accepts null for $uniqueId argument

[XFFA.IR Bot]

Code:

public function enqueueLater(string $uniqueId, int $runTime, string $jobClass, array $params = [], bool $manual = false, int $priority = 100): ?int

$uniqueId used to accept null. Thankfully an empty string works the same.

(This affects XenForo 2.2.16 too)