Merge branch '4.3' into 4.4

* 4.3:
  [Workflow] Simplified EventDispatcherMock.
  [Routing] revert the return type for UrlGeneratorInterface::generate to remove null

Author: nicolas-grekas

Tests/WorkflowTest.php

@@ -572,7 +572,7 @@ public function testGetEnabledTransitionsWithSameNameTransition()
     }
 }
 
-class EventDispatcherMock implements \Symfony\Component\EventDispatcher\EventDispatcherInterface
+class EventDispatcherMock implements \Symfony\Contracts\EventDispatcher\EventDispatcherInterface
 {
     public $dispatchedEvents = [];
 
@@ -582,32 +582,4 @@ public function dispatch($event, string $eventName = null): Event
 
         return $event;
     }
-
-    public function addListener($eventName, $listener, $priority = 0)
-    {
-    }
-
-    public function addSubscriber(\Symfony\Component\EventDispatcher\EventSubscriberInterface $subscriber)
-    {
-    }
-
-    public function removeListener($eventName, $listener)
-    {
-    }
-
-    public function removeSubscriber(\Symfony\Component\EventDispatcher\EventSubscriberInterface $subscriber)
-    {
-    }
-
-    public function getListeners($eventName = null): array
-    {
-    }
-
-    public function getListenerPriority($eventName, $listener): ?int
-    {
-    }
-
-    public function hasListeners($eventName = null): bool
-    {
-    }
 }