getExpirationDate method of IShare might return null

[jvillafanez]

Public IShare interface (OCP\Share\IShare) has method getExpirationDate which should return a \DateTime object. However, the share2.0 implementation might not return this kind of object.

• It might return null if the expiration date is not set.
• It might return any other object (not just \DateTime) if such object is set via the setExpirationDate method (no type check used in the method).

This is currently messing up with phpstan configuration, because checking if the expiration date is null is almost mandatory.

[jvillafanez]

Note that the setPassword method also has the same problem. We'll likely need to review the whole file.

[ownclouders]

GitMate.io thinks possibly related issues are #30457 (Throw exceptions instead of returning null), #10702 (OC_User::userExists(null) returns true), #21683 (owncloudcmd return ), #13862 (Throw exception in initMountPoints if user manager returned null), and #32080 (Search API might return more results than the limit).