Breaking: #93062 - Various group-related public properties in BE_USER removed
See forge#93062
Description
The PHP API class Backend was built back in
PHP4 days and had a few public properties which have been removed.
Their purpose was to store data between methods while resolving groups, where there are other methods containing all group-related information already anyways.
TYPO3\CMS\ Core\ Authentication\ Backend User Authentication->group List TYPO3\CMS\ Core\ Authentication\ Backend User Authentication->include Group Array
Impact
Accessing or setting these properties will raise a PHP warning.
Affected Installations
TYPO3 installations with third-party extensions accessing these
Backend properties, which is highly unlikely,
or because they were built 10 years ago, still accessing these properties.
Migration
Use Backend (array of group UIDs) instead,
which contains the groups in the proper order on how they were resolved.
If this is not needed directly, it is usually highly recommended to use the Context API's "backend.user" aspect to retrieve groups of a backend user.