Use numeric access to named event arguments

migrations/44-50/removed-backward-incompatibility.md

@@ -186,6 +186,16 @@ public function __construct(DispatcherInterface $dispatcher, array $config, more
 	// Assign the extra arguments to internal variables
 }
 ```
+
+### Use numeric access to named event arguments like `$event->getArgument('0')` are not recommended
+
+It is not recommended to use `$event->getArgument('0')` for events that does not have an event class. 
+In future such event will receive own class and named arguments, and this code will not work.
+
+For such events should use legacy listener, or access to argument with:
+```php
+[$arg1, $arg2] = array_values($event->getArguments());
+```
 
 ### Removed 3rd party libraries