Breaking: #87627 - Remove Property extensionName of AbstractController

See Issue #87627

Description

\TYPO3\CMS\Extbase\Mvc\Controller\AbstractController::$extensionName has been removed and is no longer available in subclasses of \TYPO3\CMS\Extbase\Mvc\Controller\AbstractController , i.e. \TYPO3\CMS\Extbase\Mvc\Controller\ActionController and their derivates.

Impact

Accessing the missing property $extensionName will throw a fatal error.

Affected Installations

All installations that read from \TYPO3\CMS\Extbase\Mvc\Controller\AbstractController::$extensionName

Migration

The extension name is set in and available through the request object that is attached to the controller. See \TYPO3\CMS\Extbase\Mvc\Controller\AbstractController::$request and \TYPO3\CMS\Extbase\Mvc\Request::getControllerExtensionName() for more information.