Undeprecate LifecycleEventArgs (doctrine#9980)

Deprecating this class means that users using SA tools have to
update their code specifying the ObjectManager implementation.

Instead of this, dedicated classes for each event should be
created before deprecating this class.

UPGRADE.md

@@ -152,10 +152,6 @@ This method has been deprecated in:
 
 It will be removed in 3.0. Use `getObjectManager()` instead.
 
-## Deprecated `Doctrine\ORM\Event\LifecycleEventArgs` class
-
-It will be removed in 3.0. Use `Doctrine\Persistence\Event\LifecycleEventArgs` instead.
-
 ## Prepare split of output walkers and tree walkers
 
 In 3.0, `SqlWalker` and its child classes won't implement the `TreeWalker`

tests/Doctrine/Tests/ORM/Functional/SecondLevelCacheTest.php

@@ -5,11 +5,11 @@
 namespace Doctrine\Tests\ORM\Functional;
 
 use Doctrine\Common\EventArgs;
+use Doctrine\ORM\Event\LifecycleEventArgs;
 use Doctrine\ORM\Event\PostFlushEventArgs;
 use Doctrine\ORM\Event\PostRemoveEventArgs;
 use Doctrine\ORM\Event\PostUpdateEventArgs;
 use Doctrine\ORM\Events;
-use Doctrine\Persistence\Event\LifecycleEventArgs;
 use Doctrine\Tests\Models\Cache\Country;
 use Doctrine\Tests\Models\Cache\State;
 use Exception;