Wrong type returned when property is null

[risototh]

I executed a request to obtain list of calendar Events, and when I call $event->getRecurrence() on Event, that does not have any recurrences, the call will return PatternedRecurrence object with empty _propDict (or better to say, it's not pointing to empty array, but to null), so the subsequent call $event->getRecurrence()->getPattern() will fail in the getPattern() method on array_key_exists() expects parameter 2 to be array, null given in /sites/freedom3/lib/vendor-composer/microsoft/microsoft-graph/src/Model/PatternedRecurrence.php on line 35.

This is because the getRecurrence() method returns null only in case, that the recurrence key is missing, not in case, that the recurrence points to null.