Wrong use of ?: causes missing attributes in CAS response

Problem/Motivation

We have noticed in our site that, after updating to 2.1.0, the attributes we were adding to the CAS response have stopped working and the following error is on the code:

Warning: foreach() argument must be of type array|object, true given in Drupal\cas_server\Controller\TicketValidationController->generateSuccessResponse() (line 383 of /var/www/html/web/modules/contrib/cas_server/src/Controller/TicketValidationController.php) 

debuggin the error: we see that in L382 of the mentioned file we have:
$value = is_array($value) ?: [$value];

so, if we are passing to the attributes (eg: via a custom alter event, like we do), certain values, if the values is not an array will be OK (cause then $value will be an array) BUT if $value is already an array, then it will be converted to bool (cause is_array will return true instead of $value)

Steps to reproduce

Test with some additional attributes of type array; those will be removed and the error will raise

Proposed resolution

Change L382 to:
$value = is_array($value) ? $value : [$value];
(will do the MR in a bit)

Remaining tasks

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