Merge pull request #11245 from nextcloud/feat/noid/smyfony-event-disp…

…atcher

fix(developer): Mention symfony/event-dispatcher

developer_manual/app_publishing_maintenance/app_upgrade_guide/upgrade_to_28.rst

@@ -13,7 +13,7 @@ Make sure your ``appinfo/info.xml`` allows for Nextcloud 28.
 .. code-block:: xml
 
     <dependencies>
-        <nextcloud min-version="25" max-version="28" />
+        <nextcloud min-version="26" max-version="28" />
     </dependencies>
 
 Front-end changes
@@ -112,6 +112,20 @@ Some (minor) breaking changes were inevitable. Here's the summary:
 
 The details of this change can also be seen in the `pull request on GitHub <https://github.com/nextcloud/server/pull/38556>`__ and in the upstream documentation `dbal 3.7.x upgrade document <https://github.com/doctrine/dbal/blob/3.7.x/UPGRADE.md>`__.
 
+``symfony/event-dispatcher``
+****************************
+
+Over the last 2 major versions the ``symfony/event-dispatcher`` package first deprecated and then removed the way Nextcloud
+server dispatched old events. This means the way we wrapped away symfony's ``\Symfony\Component\EventDispatcher\EventDispatcherInterface``
+as well as using the ``\Symfony\Component\EventDispatcher\GenericEvent`` could not be kept alive in a backwards compatible way.
+
+Therefore migrating from ``\Symfony\Component\EventDispatcher\EventDispatcherInterface``
+to ``\OCP\EventDispatcher\IEventDispatcher`` (exists since Nextcloud 17) is required to be compatible with Nextcloud 28.
+All code places that dispatched a ``\Symfony\Component\EventDispatcher\GenericEvent`` have been adjusted
+and have ``\OCP\EventDispatcher\Event`` based dedicated event now that is dispatched as a typed-event so all available parameters are documented.
+
+The details of this change can also be seen in the todo items that are linked from the `pull request on GitHub <https://github.com/nextcloud/server/pull/38546>`__.
+
 Added APIs
 ^^^^^^^^^^