Fix discriminatorValue key 0

lib/Doctrine/ODM/MongoDB/Mapping/Annotations/DiscriminatorMap.php

@@ -16,7 +16,7 @@
 #[Attribute(Attribute::TARGET_CLASS | Attribute::TARGET_PROPERTY)]
 final class DiscriminatorMap implements Annotation
 {
-    /** @var array<string, class-string> */
+    /** @var array<class-string> */
     public $value;
 
     /** @param array<string, class-string> $value */

lib/Doctrine/ODM/MongoDB/Persisters/DocumentPersister.php

@@ -1470,7 +1470,7 @@ private function getClassDiscriminatorValues(ClassMetadata $metadata): array
 
         foreach ($metadata->subClasses as $className) {
             $key = array_search($className, $metadata->discriminatorMap);
-            if (! $key) {
+            if ($key === false) {
                 continue;
             }
 

tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH2158Test.php

@@ -0,0 +1,46 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
+
+use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use Doctrine\ODM\MongoDB\Tests\BaseTestCase;
+
+class GH2158Test extends BaseTestCase
+{
+    public function testDiscriminatorMapCreationType(): void
+    {
+        $obj = new GH2158FirstType();
+        $this->dm->persist($obj);
+        $this->dm->flush();
+
+        self::assertEquals($this->dm->find(GH2158Abstract::class, $obj->getId()), $obj);
+    }
+}
+
+#[ODM\Document(collection: 'documents')]
+#[ODM\InheritanceType('SINGLE_COLLECTION')]
+#[ODM\DiscriminatorField('type')]
+#[ODM\DiscriminatorMap([0 => GH2158FirstType::class, 1 => GH2158SecondType::class])]
+abstract class GH2158Abstract
+{
+    /** @var string */
+    #[ODM\Id]
+    protected $id;
+
+    public function getId(): string
+    {
+        return $this->id;
+    }
+}
+
+#[ODM\Document]
+class GH2158FirstType extends GH2158Abstract
+{
+}
+
+#[ODM\Document]
+class GH2158SecondType extends GH2158Abstract
+{
+}