IBX-7055: Made BeforeTrashEvent::getResult return value nullable (#297)

For more details see https://issues.ibexa.co/browse/IBX-7055 and #297

Key changes:

* Allowed to return `null` from `BeforeTrashEvent::getResult` when content Location is not trashed

* [Tests] Added test coverage

phpstan-baseline.neon

@@ -6220,11 +6220,6 @@ parameters:
 			count: 1
 			path: src/contracts/Repository/Events/Trash/BeforeRecoverEvent.php
 
-		-
-			message: "#^Method Ibexa\\\\Contracts\\\\Core\\\\Repository\\\\Events\\\\Trash\\\\BeforeTrashEvent\\:\\:getResult\\(\\) should return Ibexa\\\\Contracts\\\\Core\\\\Repository\\\\Values\\\\Content\\\\TrashItem but returns Ibexa\\\\Contracts\\\\Core\\\\Repository\\\\Values\\\\Content\\\\TrashItem\\|null\\.$#"
-			count: 1
-			path: src/contracts/Repository/Events/Trash/BeforeTrashEvent.php
-
 		-
 			message: "#^Property Ibexa\\\\Contracts\\\\Core\\\\Repository\\\\Events\\\\Trash\\\\RecoverEvent\\:\\:\\$newParentLocation \\(Ibexa\\\\Contracts\\\\Core\\\\Repository\\\\Values\\\\Content\\\\Location\\) does not accept Ibexa\\\\Contracts\\\\Core\\\\Repository\\\\Values\\\\Content\\\\Location\\|null\\.$#"
 			count: 1

src/contracts/Repository/Events/Trash/BeforeTrashEvent.php

@@ -34,7 +34,7 @@ public function getLocation(): Location
         return $this->location;
     }
 
-    public function getResult(): TrashItem
+    public function getResult(): ?TrashItem
     {
         if (!$this->isResultSet()) {
             throw new UnexpectedValueException(sprintf('Return value is not set or not of type %s (or null). Check isResultSet() or set it using setResult() before you call the getter.', TrashItem::class));

tests/lib/Event/TrashServiceTest.php

@@ -218,6 +218,41 @@ public function testTrashStopPropagationInBeforeEvents()
         ]);
     }
 
+    public function testTrashStopPropagationInBeforeEventsSetsNullResult(): void
+    {
+        $traceableEventDispatcher = $this->getEventDispatcher(
+            BeforeTrashEvent::class,
+            TrashEvent::class
+        );
+
+        $parameters = [
+            $this->createMock(Location::class),
+        ];
+
+        $innerServiceMock = $this->createMock(TrashServiceInterface::class);
+        $innerServiceMock->expects(self::never())->method('trash');
+
+        $traceableEventDispatcher->addListener(BeforeTrashEvent::class, static function (BeforeTrashEvent $event) {
+            $event->setResult(null);
+            $event->stopPropagation();
+        }, 10);
+
+        $service = new TrashService($innerServiceMock, $traceableEventDispatcher);
+        $result = $service->trash(...$parameters);
+
+        $calledListeners = $this->getListenersStack($traceableEventDispatcher->getCalledListeners());
+        $notCalledListeners = $this->getListenersStack($traceableEventDispatcher->getNotCalledListeners());
+
+        self::assertNull($result);
+        self::assertSame($calledListeners, [
+            [BeforeTrashEvent::class, 10],
+        ]);
+        self::assertSame($notCalledListeners, [
+            [BeforeTrashEvent::class, 0],
+            [TrashEvent::class, 0],
+        ]);
+    }
+
     public function testRecoverEvents()
     {
         $traceableEventDispatcher = $this->getEventDispatcher(