diff --git a/benchmark/BaseBench.php b/benchmark/BaseBench.php
index 90283821ca..1232fb3b54 100644
--- a/benchmark/BaseBench.php
+++ b/benchmark/BaseBench.php
@@ -28,15 +28,12 @@ abstract class BaseBench
     /** @var DocumentManager */
     protected static $documentManager;
 
-    /**
-     * @return DocumentManager
-     */
-    protected function getDocumentManager()
+    protected function getDocumentManager(): DocumentManager
     {
         return self::$documentManager;
     }
 
-    public function initDocumentManager()
+    public function initDocumentManager(): void
     {
         $config = new Configuration();
 
@@ -59,7 +56,7 @@ public function initDocumentManager()
         self::$documentManager = DocumentManager::create($client, $config);
     }
 
-    public function clearDatabase()
+    public function clearDatabase(): void
     {
         // Check if the database exists. Calling listCollections on a non-existing
         // database in a sharded setup will cause an invalid command cursor to be
@@ -85,7 +82,7 @@ public function clearDatabase()
         }
     }
 
-    protected static function createMetadataDriverImpl()
+    protected static function createMetadataDriverImpl(): AnnotationDriver
     {
         return AnnotationDriver::create(__DIR__ . '/../tests/Documents');
     }
diff --git a/benchmark/Document/LoadDocumentBench.php b/benchmark/Document/LoadDocumentBench.php
index f36ae007de..88bcd4edd5 100644
--- a/benchmark/Document/LoadDocumentBench.php
+++ b/benchmark/Document/LoadDocumentBench.php
@@ -25,7 +25,7 @@ final class LoadDocumentBench extends BaseBench
     /** @var ObjectId */
     private static $userId;
 
-    public function init()
+    public function init(): void
     {
         self::$userId = new ObjectId();
 
@@ -58,7 +58,7 @@ public function init()
     /**
      * @Warmup(2)
      */
-    public function benchLoadDocument()
+    public function benchLoadDocument(): void
     {
         $this->loadDocument();
     }
@@ -66,7 +66,7 @@ public function benchLoadDocument()
     /**
      * @Warmup(2)
      */
-    public function benchLoadEmbedOne()
+    public function benchLoadEmbedOne(): void
     {
         $this->loadDocument()->getAddress()->getCity();
     }
@@ -74,7 +74,7 @@ public function benchLoadEmbedOne()
     /**
      * @Warmup(2)
      */
-    public function benchLoadEmbedMany()
+    public function benchLoadEmbedMany(): void
     {
         $this->loadDocument()->getPhonenumbers()->forAll(static function (int $key, Phonenumber $element) {
             return $element->getPhoneNumber() !== null;
@@ -94,8 +94,8 @@ public function benchLoadReferenceOne()
      */
     public function benchLoadReferenceMany()
     {
-        $this->loadDocument()->getGroups()->forAll(static function ($key, Group $group) {
-            return $group->getName();
+        $this->loadDocument()->getGroups()->forAll(static function (int $key, Group $group) {
+            return $group->getName() !== null;
         });
     }
 
diff --git a/lib/Doctrine/ODM/MongoDB/DocumentManager.php b/lib/Doctrine/ODM/MongoDB/DocumentManager.php
index f56cc092d1..a335b6fae5 100644
--- a/lib/Doctrine/ODM/MongoDB/DocumentManager.php
+++ b/lib/Doctrine/ODM/MongoDB/DocumentManager.php
@@ -316,6 +316,8 @@ public function getClassMetadata($className): ClassMetadata
 
     /**
      * Returns the MongoDB instance for a class.
+     *
+     * @psalm-param class-string $className
      */
     public function getDocumentDatabase(string $className): Database
     {
diff --git a/phpcs.xml.dist b/phpcs.xml.dist
index 28f247ed9d..1543cd4ce7 100644
--- a/phpcs.xml.dist
+++ b/phpcs.xml.dist
@@ -33,7 +33,6 @@
         <!-- Will cause BC breaks to method signatures - disabled for now -->
         <exclude name="SlevomatCodingStandard.TypeHints.ParameterTypeHint.MissingAnyTypeHint" />
         <exclude name="SlevomatCodingStandard.TypeHints.ParameterTypeHint.MissingNativeTypeHint" />
-        <exclude name="SlevomatCodingStandard.TypeHints.ReturnTypeHint.MissingAnyTypeHint" />
         <exclude name="SlevomatCodingStandard.TypeHints.ReturnTypeHint.MissingNativeTypeHint" />
 
         <!-- Disabled to avoid class renaming - to be handled in a separate PR -->
@@ -67,6 +66,10 @@
         <exclude-pattern>*/tests/*</exclude-pattern>
     </rule>
 
+    <rule ref="SlevomatCodingStandard.TypeHints.ReturnTypeHint.MissingAnyTypeHint">
+        <exclude-pattern>*/lib/*</exclude-pattern>
+    </rule>
+
     <rule ref="SlevomatCodingStandard.TypeHints.ReturnTypeHint.MissingNativeTypeHint">
         <!-- We do want to test generating collections without return types -->
         <exclude-pattern>*/tests/Doctrine/ODM/MongoDB/Tests/PersistentCollection/Coll*</exclude-pattern>
diff --git a/phpstan-baseline.neon b/phpstan-baseline.neon
index 94229f8114..0385b292e3 100644
--- a/phpstan-baseline.neon
+++ b/phpstan-baseline.neon
@@ -59,11 +59,6 @@ parameters:
             count: 1
             path: tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomFieldNameTest.php
 
-        -
-            message: "#^Offset 'userId' does not exist on array\\(\\)\\|array\\('ids' \\=\\> array\\<int, mixed\\>&nonEmpty, \\?'userId' \\=\\> true\\)\\.$#"
-            count: 1
-            path: tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomIdTest.php
-
         -
             message: "#^Cannot call method current\\(\\) on array\\|int\\|object\\.$#"
             count: 1
@@ -229,3 +224,9 @@ parameters:
             message: "#^Unreachable statement \\- code above always terminates\\.$#"
             count: 1
             path: lib/Doctrine/ODM/MongoDB/Types/DateImmutableType.php
+
+        # See https://github.com/phpstan/phpstan/issues/5512
+        -
+            message: "#^Method Doctrine\\\\ODM\\\\MongoDB\\\\Tests\\\\Functional\\\\My.*Collection\\:\\:.*\\(\\) should return Doctrine\\\\ODM\\\\MongoDB\\\\Tests\\\\Functional\\\\My.*Collection but returns Doctrine\\\\Common\\\\Collections\\\\ArrayCollection\\<\\(int\\|string\\), mixed\\>\\.$#"
+            count: 3
+            path: tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomCollectionsTest.php
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/BaseTest.php b/tests/Doctrine/ODM/MongoDB/Tests/BaseTest.php
index 3834aad803..eea0333167 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/BaseTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/BaseTest.php
@@ -104,10 +104,7 @@ public static function assertArraySubset($subset, $array, bool $checkForObjectId
         }
     }
 
-    /**
-     * @return MappingDriver
-     */
-    protected function createMetadataDriverImpl()
+    protected function createMetadataDriverImpl(): MappingDriver
     {
         return AnnotationDriver::create(__DIR__ . '/../../../../Documents');
     }
@@ -120,14 +117,17 @@ protected function createTestDocumentManager(): DocumentManager
         return DocumentManager::create($client, $config);
     }
 
-    protected function getServerVersion()
+    protected function getServerVersion(): string
     {
         $result = $this->dm->getClient()->selectDatabase(DOCTRINE_MONGODB_DATABASE)->command(['buildInfo' => 1])->toArray()[0];
 
         return $result['version'];
     }
 
-    protected function skipTestIfNotSharded($className): void
+    /**
+     * @psalm-param class-string $className
+     */
+    protected function skipTestIfNotSharded(string $className): void
     {
         $result = $this->dm->getDocumentDatabase($className)->command(['listCommands' => true])->toArray()[0];
 
@@ -138,7 +138,10 @@ protected function skipTestIfNotSharded($className): void
         $this->markTestSkipped('Test skipped because server does not support sharding');
     }
 
-    protected function skipTestIfSharded($className): void
+    /**
+     * @psalm-param class-string $className
+     */
+    protected function skipTestIfSharded(string $className): void
     {
         $result = $this->dm->getDocumentDatabase($className)->command(['listCommands' => true])->toArray()[0];
 
@@ -149,7 +152,7 @@ protected function skipTestIfSharded($className): void
         $this->markTestSkipped('Test does not apply on sharded clusters');
     }
 
-    protected function requireVersion($installedVersion, $requiredVersion, $operator, $message): void
+    protected function requireVersion(string $installedVersion, string $requiredVersion, ?string $operator, string $message): void
     {
         if (! version_compare($installedVersion, $requiredVersion, $operator)) {
             return;
@@ -158,12 +161,12 @@ protected function requireVersion($installedVersion, $requiredVersion, $operator
         $this->markTestSkipped($message);
     }
 
-    protected function skipOnMongoDB42($message): void
+    protected function skipOnMongoDB42(string $message): void
     {
         $this->requireVersion($this->getServerVersion(), '4.2.0', '>=', $message);
     }
 
-    protected function requireMongoDB42($message): void
+    protected function requireMongoDB42(string $message): void
     {
         $this->requireVersion($this->getServerVersion(), '4.2.0', '<', $message);
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomCollectionsTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomCollectionsTest.php
index 4470c26df6..5b6265f5ff 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomCollectionsTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomCollectionsTest.php
@@ -277,14 +277,14 @@ public function __construct(string $name, bool $enabled)
 
 class MyEmbedsCollection extends ArrayCollection
 {
-    public function getByName($name)
+    public function getByName(string $name): MyEmbedsCollection
     {
         return $this->filter(static function ($item) use ($name) {
             return $item->name === $name;
         });
     }
 
-    public function getEnabled()
+    public function getEnabled(): MyEmbedsCollection
     {
         return $this->filter(static function ($item) {
             return $item->enabled;
@@ -305,7 +305,7 @@ public function nothingReally(): void
 
 class MyDocumentsCollection extends ArrayCollection
 {
-    public function havingEmbeds()
+    public function havingEmbeds(): MyDocumentsCollection
     {
         return $this->filter(static function ($item) {
             return $item->coll->count();
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomIdTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomIdTest.php
index 7f9159c2e8..3b37552b81 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomIdTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomIdTest.php
@@ -81,7 +81,7 @@ public function testBatchInsertCustomId(): void
 
         $this->assertCount(2, $users);
 
-        $results = [];
+        $results = ['userId' => false];
         foreach ($users as $user) {
             if ($user->getId() === 'userId') {
                 $results['userId'] = true;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomTypeTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomTypeTest.php
index 4c64181dd0..ccf29dfc3b 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomTypeTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/CustomTypeTest.php
@@ -54,6 +54,8 @@ class DateCollectionType extends Type
 
     /**
      * Method called by PersistenceBuilder
+     *
+     * {@inheritDoc}
      */
     public function convertToDatabaseValue($value)
     {
@@ -74,6 +76,9 @@ public function convertToDatabaseValue($value)
         return $value;
     }
 
+    /**
+     * {@inheritDoc}
+     */
     public function convertToPHPValue($value)
     {
         if ($value === null) {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/DiscriminatorsDefaultValueTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/DiscriminatorsDefaultValueTest.php
index a398ff393f..a1c56b78ae 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/DiscriminatorsDefaultValueTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/DiscriminatorsDefaultValueTest.php
@@ -90,18 +90,21 @@ abstract class ParentDocument
      */
     protected $id;
 
-    /** @var ChildDocument|null */
+    /** @var ChildDocument */
     protected $referencedChild;
 
-    /** @var ChildDocument[] */
+    /** @var Collection<int, ChildDocument>|array<ChildDocument> */
     protected $referencedChildren;
 
-    /** @var ChildDocument|null */
+    /** @var ChildDocument */
     protected $embeddedChild;
 
-    /** @var ChildDocument[]  */
+    /** @var Collection<int, ChildDocument>|array<ChildDocument> */
     protected $embeddedChildren;
 
+    /**
+     * @param array{0: ChildDocument, 1: ChildDocument} $children
+     */
     public function __construct(array $children)
     {
         $this->referencedChild    = $children[0];
@@ -115,21 +118,27 @@ public function getId(): ?string
         return $this->id;
     }
 
-    public function getReferencedChild()
+    public function getReferencedChild(): ChildDocument
     {
         return $this->referencedChild;
     }
 
+    /**
+     * @return Collection<int, ChildDocument>|array<ChildDocument>
+     */
     public function getReferencedChildren()
     {
         return $this->referencedChildren;
     }
 
-    public function getEmbeddedChild()
+    public function getEmbeddedChild(): ChildDocument
     {
         return $this->embeddedChild;
     }
 
+    /**
+     * @return Collection<int, ChildDocument>|array<ChildDocument>
+     */
     public function getEmbeddedChildren()
     {
         return $this->embeddedChildren;
@@ -158,12 +167,12 @@ public function __construct(string $type)
         $this->type = $type;
     }
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
 
-    public function getType()
+    public function getType(): string
     {
         return $this->type;
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/DocumentPersisterTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/DocumentPersisterTest.php
index b5b4dcf432..c9f227331b 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/DocumentPersisterTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/DocumentPersisterTest.php
@@ -1035,6 +1035,9 @@ final class DocumentPersisterCustomIdType extends Type
 {
     use ClosureToPHP;
 
+    /**
+     * {@inheritdoc}
+     */
     public function convertToDatabaseValue($value)
     {
         if ($value instanceof ObjectId) {
@@ -1048,6 +1051,9 @@ public function convertToDatabaseValue($value)
         throw self::createException($value);
     }
 
+    /**
+     * {@inheritdoc}
+     */
     public function convertToPHPValue($value)
     {
         if ($value instanceof DocumentPersisterCustomTypedId) {
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/EcommerceTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/EcommerceTest.php
index bd552e5f17..fcf128bb74 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/EcommerceTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/EcommerceTest.php
@@ -86,7 +86,7 @@ public function testRemoveOption(): void
         $this->assertCount(2, $product->getOptions());
     }
 
-    protected function getProduct()
+    protected function getProduct(): ConfigurableProduct
     {
         $products = $this->dm->getRepository(ConfigurableProduct::class)
             ->createQueryBuilder()
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/FilterTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/FilterTest.php
index 8931c85f63..ad7d557dd7 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/FilterTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/FilterTest.php
@@ -157,7 +157,7 @@ public function testRepositoryFindOneBy(): void
         $this->assertEquals('John', $this->getJohnsUsernameWithFindOneBy());
     }
 
-    protected function getJohnsUsernameWithFindOneBy()
+    protected function getJohnsUsernameWithFindOneBy(): ?string
     {
         $john = $this->dm->getRepository(User::class)->findOneBy(['id' => $this->ids['john']]);
 
@@ -235,7 +235,7 @@ public function testReferenceOne(): void
         $this->assertEquals('Timothy', $this->getProfileByReference());
     }
 
-    protected function getProfileByReference()
+    protected function getProfileByReference(): ?string
     {
         $tim = $this->dm->getRepository(User::class)->find($this->ids['tim']);
 
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/IdentifiersTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/IdentifiersTest.php
index e48cee20af..75e7804761 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/IdentifiersTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/IdentifiersTest.php
@@ -7,6 +7,7 @@
 use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Event;
 use Documents\User;
+use ProxyManager\Proxy\LazyLoadingInterface;
 
 use function assert;
 use function get_class;
@@ -27,8 +28,10 @@ public function testGetIdentifierValue(): void
 
         $test = $this->dm->getRepository(get_class($event))->find($event->getId());
 
-        $this->assertEquals($user->getId(), $test->getUser()->getId());
-        $this->assertFalse($test->getUser()->isProxyInitialized());
+        $userTest = $test->getUser();
+        $this->assertEquals($user->getId(), $userTest->getId());
+        $this->assertInstanceOf(LazyLoadingInterface::class, $userTest);
+        $this->assertFalse($userTest->isProxyInitialized());
 
         $this->dm->clear();
 
@@ -37,6 +40,7 @@ public function testGetIdentifierValue(): void
         $test = $this->dm->getRepository(get_class($event))->find($event->getId());
         $this->assertEquals($user->getId(), $class->getIdentifierValue($test->getUser()));
         $this->assertEquals($user->getId(), $class->getFieldValue($test->getUser(), 'id'));
+        $this->assertInstanceOf(LazyLoadingInterface::class, $test->getUser());
         $this->assertFalse($test->getUser()->isProxyInitialized());
 
         $this->assertEquals('jwage', $test->getUser()->getUsername());
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/MappedSuperclassTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/MappedSuperclassTest.php
index 41f704bdd0..6d81a510ed 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/MappedSuperclassTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/MappedSuperclassTest.php
@@ -67,7 +67,7 @@ public function setMapped1($val): void
         $this->mapped1 = $val;
     }
 
-    public function getMapped1()
+    public function getMapped1(): ?string
     {
         return $this->mapped1;
     }
@@ -77,7 +77,7 @@ public function setMapped2($val): void
         $this->mapped2 = $val;
     }
 
-    public function getMapped2()
+    public function getMapped2(): ?string
     {
         return $this->mapped2;
     }
@@ -87,7 +87,7 @@ public function setMappedRelated1($mappedRelated1): void
         $this->mappedRelated1 = $mappedRelated1;
     }
 
-    public function getMappedRelated1()
+    public function getMappedRelated1(): ?MappedSuperclassRelated1
     {
         return $this->mappedRelated1;
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/NestedDocumentsTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/NestedDocumentsTest.php
index 8b15a2fb2d..81ffcda4ed 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/NestedDocumentsTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/NestedDocumentsTest.php
@@ -112,8 +112,8 @@ public function testNestedReference(): void
         $test = $this->dm->getRepository(Hierarchy::class)->findOneBy(['name' => 'Root']);
 
         $this->assertNotNull($test);
-        $child1 = $test->getChild('Child 1')->setName('Child 1 Changed');
-        $child2 = $test->getChild('Child 2')->setName('Child 2 Changed');
+        $test->getChild('Child 1')->setName('Child 1 Changed');
+        $test->getChild('Child 2')->setName('Child 2 Changed');
         $test->setName('Root Changed');
         $child3 = $test->addChild('Child 3');
         $this->dm->persist($child3);
@@ -184,6 +184,11 @@ public function getName(): string
         return $this->name;
     }
 
+    /**
+     * @param int|string $name
+     *
+     * @return Hierarchy|null
+     */
     public function getChild($name)
     {
         if (is_numeric($name)) {
@@ -199,6 +204,11 @@ public function getChild($name)
         return null;
     }
 
+    /**
+     * @param string|Hierarchy $child
+     *
+     * @return Hierarchy
+     */
     public function addChild($child)
     {
         if (is_string($child)) {
@@ -210,7 +220,10 @@ public function addChild($child)
         return $child;
     }
 
-    public function getChildren(): array
+    /**
+     * @return Collection<int, Hierarchy>|array<Hierarchy>
+     */
+    public function getChildren()
     {
         return $this->children;
     }
@@ -249,6 +262,11 @@ public function getName(): string
         return $this->name;
     }
 
+    /**
+     * @param string|int $name
+     *
+     * @return ChildCategory|null
+     */
     public function getChild($name)
     {
         if (is_numeric($name)) {
@@ -264,6 +282,11 @@ public function getChild($name)
         return null;
     }
 
+    /**
+     * @param string|ChildCategory $child
+     *
+     * @return ChildCategory
+     */
     public function addChild($child)
     {
         if (is_string($child)) {
@@ -275,6 +298,9 @@ public function addChild($child)
         return $child;
     }
 
+    /**
+     * @return Collection<int, ChildCategory>
+     */
     public function getChildren(): Collection
     {
         return $this->children;
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferencesTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferencesTest.php
index 153f2aa926..7e004b7fee 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferencesTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/ReferencesTest.php
@@ -11,6 +11,7 @@
 use Doctrine\ODM\MongoDB\Iterator\Iterator;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use Doctrine\ODM\MongoDB\PersistentCollection;
+use Doctrine\ODM\MongoDB\PersistentCollection\PersistentCollectionInterface;
 use Doctrine\ODM\MongoDB\Tests\BaseTest;
 use Documents\Account;
 use Documents\Address;
@@ -206,6 +207,7 @@ public function testManyReference(): void
         $user2 = $query->getSingleResult();
         assert($user2 instanceof User);
         $groups = $user2->getGroups();
+        $this->assertInstanceOf(PersistentCollectionInterface::class, $groups);
         $this->assertFalse($groups->isInitialized());
 
         $groups->count();
@@ -255,6 +257,7 @@ public function testFlushInitializesEmptyPersistentCollection(): void
         $this->dm->persist($user);
         $this->dm->flush();
 
+        $this->assertInstanceOf(PersistentCollectionInterface::class, $user->getGroups());
         $this->assertTrue($user->getGroups()->isInitialized(), 'A flushed collection should be initialized');
         $this->assertCount(2, $user->getGroups());
         $this->assertCount(2, $user->getGroups()->toArray());
@@ -277,6 +280,7 @@ public function testFlushInitializesNotEmptyPersistentCollection(): void
         $this->dm->persist($user);
         $this->dm->flush();
 
+        $this->assertInstanceOf(PersistentCollectionInterface::class, $user->getGroups());
         $this->assertTrue($user->getGroups()->isInitialized(), 'A flushed collection should be initialized');
         $this->assertCount(3, $user->getGroups());
         $this->assertCount(3, $user->getGroups()->toArray());
@@ -308,6 +312,7 @@ public function testManyReferenceWithAddToSetStrategy(): void
         assert($user2 instanceof User);
 
         $groups = $user2->getUniqueGroups();
+        $this->assertInstanceOf(PersistentCollection\PersistentCollectionInterface::class, $groups);
         $this->assertFalse($groups->isInitialized());
 
         $groups->count();
@@ -495,6 +500,7 @@ public function testDocumentNotFoundEvent(): void
 
         $this->dm->getEventManager()->addEventListener(Events::documentNotFound, new DocumentNotFoundListener($closure));
 
+        $this->assertInstanceOf(LazyLoadingInterface::class, $profile);
         $profile->initializeProxy();
     }
 }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1058Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1058Test.php
index afd21af33c..a8662908cc 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1058Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH1058Test.php
@@ -78,7 +78,7 @@ class GH1058PersistDocument
      */
     private $value;
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
@@ -106,7 +106,7 @@ class GH1058UpsertDocument
      */
     private $value;
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH267Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH267Test.php
index fccb5115a0..f0dc77b84d 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH267Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH267Test.php
@@ -93,7 +93,7 @@ public function setId(string $id): void
         $this->id = $id;
     }
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
@@ -146,7 +146,7 @@ public function setId($id): void
         $this->id = $id;
     }
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH593Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH593Test.php
index ff1100568c..d60685c1c6 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH593Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH593Test.php
@@ -138,7 +138,7 @@ public function __construct()
     }
 
     /** Return the identifier without triggering Proxy initialization */
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH597Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH597Test.php
index 161427d8c1..ca6cf2db14 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH597Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH597Test.php
@@ -150,7 +150,7 @@ public function __construct()
         $this->referenceMany = new ArrayCollection();
     }
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
@@ -205,7 +205,7 @@ public function __construct($field)
         $this->field = $field;
     }
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH602Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH602Test.php
index 98e9e26d16..67b894ee18 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH602Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH602Test.php
@@ -132,7 +132,7 @@ public function __construct()
     }
 
     /** Return the identifier without triggering Proxy initialization */
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH774Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH774Test.php
index 6fe761f79b..e42169bc53 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH774Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH774Test.php
@@ -6,6 +6,7 @@
 
 use Doctrine\ODM\MongoDB\Mapping\Driver\XmlDriver;
 use Doctrine\ODM\MongoDB\Tests\BaseTest;
+use Doctrine\Persistence\Mapping\Driver\MappingDriver;
 use MongoDB\BSON\ObjectId;
 
 use function get_class;
@@ -29,7 +30,7 @@ public function testUpsert(): void
         $this->assertEquals('test', $thread->permalink);
     }
 
-    protected function createMetadataDriverImpl()
+    protected function createMetadataDriverImpl(): MappingDriver
     {
         return new XmlDriver(__DIR__ . '/GH774');
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH909Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH909Test.php
index d317b52940..52ac8bfba6 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH909Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH909Test.php
@@ -26,6 +26,7 @@ public function testManyReferenceAddAndPersist(): void
 
         $groups = $user->getGroups();
         $this->assertCount(2, $groups);
+        $this->assertInstanceOf(PersistentCollectionInterface::class, $groups);
         $this->assertTrue($groups->isInitialized());
 
         $user->addGroup(new Group('Group C'));
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH999Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH999Test.php
index 89dbc8f123..a241920d82 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH999Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/GH999Test.php
@@ -65,12 +65,12 @@ public function __construct($name)
         $this->name = $name;
     }
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
 
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM45Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM45Test.php
index 277287e4de..1002f3c6a6 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM45Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM45Test.php
@@ -72,7 +72,7 @@ public function setVal($val): void
         $this->val = $val;
     }
 
-    public function getVal()
+    public function getVal(): ?string
     {
         return $this->val;
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM47Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM47Test.php
index e7f238b8ac..0e84982640 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM47Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM47Test.php
@@ -46,7 +46,7 @@ public function renameC($c): void
         $this->b = $c;
     }
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM48Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM48Test.php
index 136f181465..101642d270 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM48Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM48Test.php
@@ -47,12 +47,12 @@ class MODM48A
      */
     public $b;
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
 
-    public function getB()
+    public function getB(): ?MODM48B
     {
         return $this->b;
     }
@@ -78,7 +78,7 @@ public function setVal($val): void
         $this->val = $val;
     }
 
-    public function getVal()
+    public function getVal(): ?string
     {
         return $this->val;
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM70Test.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM70Test.php
index 08971dfac8..fb394a8514 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM70Test.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Ticket/MODM70Test.php
@@ -4,6 +4,7 @@
 
 namespace Doctrine\ODM\MongoDB\Tests\Functional\Ticket;
 
+use Doctrine\Common\Collections\Collection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 use Doctrine\ODM\MongoDB\Tests\BaseTest;
 
@@ -62,18 +63,21 @@ class Avatar
      *  name="aP"
      * )
      *
-     * @var array AvatarPart
+     * @var Collection<int, AvatarPart>|array<AvatarPart>
      */
     protected $avatarParts;
 
-    public function __construct($name, $sex, $avatarParts = null)
+    /**
+     * @param AvatarPart[] $avatarParts
+     */
+    public function __construct(string $name, int $sex, ?array $avatarParts = null)
     {
         $this->name        = $name;
         $this->sex         = $sex;
         $this->avatarParts = $avatarParts;
     }
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
@@ -83,7 +87,7 @@ public function getName(): string
         return $this->name;
     }
 
-    public function setName($name): void
+    public function setName(string $name): void
     {
         $this->name = $name;
     }
@@ -93,29 +97,35 @@ public function getSex(): int
         return $this->sex;
     }
 
-    public function setSex($sex): void
+    public function setSex(int $sex): void
     {
         $this->sex = $sex;
     }
 
+    /**
+     * @return Collection<int, AvatarPart>|array<AvatarPart>|null
+     */
     public function getAvatarParts()
     {
         return $this->avatarParts;
     }
 
-    public function addAvatarPart($part): void
+    public function addAvatarPart(AvatarPart $part): void
     {
         $this->avatarParts[] = $part;
     }
 
-    public function setAvatarParts($parts): void
+    /**
+     * @param AvatarPart[] $parts
+     */
+    public function setAvatarParts(array $parts): void
     {
         $this->avatarParts = $parts;
     }
 
-    public function removeAvatarPart($part): void
+    public function removeAvatarPart(AvatarPart $part): void
     {
-        $key = array_search($this->avatarParts, $part);
+        $key = array_search($part, $this->avatarParts);
         if ($key === false) {
             return;
         }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/UpsertTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/UpsertTest.php
index 6d4bc16515..0cfefb400c 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/UpsertTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/UpsertTest.php
@@ -38,7 +38,7 @@ public function testUpsertEmbedManyDoesNotCreateObject(): void
         $this->dm->flush();
     }
 
-    public function testUpsertDoesNotOverwriteNullableFieldsOnNull()
+    public function testUpsertDoesNotOverwriteNullableFieldsOnNull(): void
     {
         $test = new UpsertTestUser();
 
@@ -66,7 +66,7 @@ public function testUpsertDoesNotOverwriteNullableFieldsOnNull()
         self::assertNotNull($upsertResult->nullableEmbedOne);
     }
 
-    public function testUpsertsWritesNullableFieldsOnInsert()
+    public function testUpsertsWritesNullableFieldsOnInsert(): void
     {
         $test = new UpsertTestUser();
         $this->dm->persist($test);
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/AbstractAnnotationDriverTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/AbstractAnnotationDriverTest.php
index 74caf1fcbd..cbdd5876a8 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/AbstractAnnotationDriverTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/AbstractAnnotationDriverTest.php
@@ -10,13 +10,14 @@
 use Doctrine\ODM\MongoDB\Mapping\Driver\AnnotationDriver;
 use Doctrine\ODM\MongoDB\Mapping\MappingException;
 use Documents\CmsUser;
+use Generator;
 use stdClass;
 
 use function get_class;
 
 abstract class AbstractAnnotationDriverTest extends AbstractMappingDriverTest
 {
-    public function testFieldInheritance()
+    public function testFieldInheritance(): void
     {
         // @TODO: This can be a generic test for all drivers
         $super  = $this->dm->getClassMetadata(AnnotationDriverTestSuper::class);
@@ -71,7 +72,7 @@ public function testFieldInheritance()
     /**
      * @group DDC-268
      */
-    public function testLoadMetadataForNonDocumentThrowsException()
+    public function testLoadMetadataForNonDocumentThrowsException(): void
     {
         $cm               = new ClassMetadata('stdClass');
         $reader           = new AnnotationReader();
@@ -84,7 +85,7 @@ public function testLoadMetadataForNonDocumentThrowsException()
     /**
      * @group DDC-268
      */
-    public function testColumnWithMissingTypeDefaultsToString()
+    public function testColumnWithMissingTypeDefaultsToString(): void
     {
         $cm               = new ClassMetadata(ColumnWithoutType::class);
         $reader           = new AnnotationReader();
@@ -97,7 +98,7 @@ public function testColumnWithMissingTypeDefaultsToString()
     /**
      * @group DDC-318
      */
-    public function testGetAllClassNamesIsIdempotent()
+    public function testGetAllClassNamesIsIdempotent(): void
     {
         $annotationDriver = $this->loadDriverForCMSDocuments();
         $original         = $annotationDriver->getAllClassNames();
@@ -111,7 +112,7 @@ public function testGetAllClassNamesIsIdempotent()
     /**
      * @group DDC-318
      */
-    public function testGetAllClassNamesIsIdempotentEvenWithDifferentDriverInstances()
+    public function testGetAllClassNamesIsIdempotentEvenWithDifferentDriverInstances(): void
     {
         $annotationDriver = $this->loadDriverForCMSDocuments();
         $original         = $annotationDriver->getAllClassNames();
@@ -125,7 +126,7 @@ public function testGetAllClassNamesIsIdempotentEvenWithDifferentDriverInstances
     /**
      * @group DDC-318
      */
-    public function testGetAllClassNamesReturnsAlreadyLoadedClassesIfAppropriate()
+    public function testGetAllClassNamesReturnsAlreadyLoadedClassesIfAppropriate(): void
     {
         $annotationDriver = $this->loadDriverForCMSDocuments();
         $classes          = $annotationDriver->getAllClassNames();
@@ -136,7 +137,7 @@ public function testGetAllClassNamesReturnsAlreadyLoadedClassesIfAppropriate()
     /**
      * @group DDC-318
      */
-    public function testGetClassNamesReturnsOnlyTheAppropriateClasses()
+    public function testGetClassNamesReturnsOnlyTheAppropriateClasses(): void
     {
         $extraneousClassName = ColumnWithoutType::class;
 
@@ -146,14 +147,14 @@ public function testGetClassNamesReturnsOnlyTheAppropriateClasses()
         $this->assertNotContains($extraneousClassName, $classes);
     }
 
-    public function testEmbeddedClassCantHaveShardKey()
+    public function testEmbeddedClassCantHaveShardKey(): void
     {
         $this->expectException(MappingException::class);
         $this->expectExceptionMessage('Embedded document can\'t have shard key');
         $this->dm->getClassMetadata(AnnotationDriverEmbeddedWithShardKey::class);
     }
 
-    public function testDocumentAnnotationCanSpecifyWriteConcern()
+    public function testDocumentAnnotationCanSpecifyWriteConcern(): void
     {
         $cm = $this->dm->getClassMetadata(AnnotationDriverTestWriteConcernMajority::class);
         $this->assertEquals('majority', $cm->writeConcern);
@@ -168,7 +169,7 @@ public function testDocumentAnnotationCanSpecifyWriteConcern()
     /**
      * @dataProvider provideClassCanBeMappedByOneAbstractDocument
      */
-    public function testClassCanBeMappedByOneAbstractDocument(object $wrong, string $messageRegExp)
+    public function testClassCanBeMappedByOneAbstractDocument(object $wrong, string $messageRegExp): void
     {
         $this->expectException(MappingException::class);
         $this->expectExceptionMessageMatches($messageRegExp);
@@ -180,7 +181,7 @@ public function testClassCanBeMappedByOneAbstractDocument(object $wrong, string
         $annotationDriver->loadMetadataForClass(get_class($wrong), $cm);
     }
 
-    public function provideClassCanBeMappedByOneAbstractDocument()
+    public function provideClassCanBeMappedByOneAbstractDocument(): ?Generator
     {
         yield [
             /**
@@ -243,7 +244,7 @@ public function provideClassCanBeMappedByOneAbstractDocument()
         ];
     }
 
-    public function testWrongValueForValidationValidatorShouldThrowException()
+    public function testWrongValueForValidationValidatorShouldThrowException(): void
     {
         $annotationDriver = $this->loadDriver();
         $classMetadata    = new ClassMetadata(WrongValueForValidationValidator::class);
@@ -252,7 +253,7 @@ public function testWrongValueForValidationValidatorShouldThrowException()
         $annotationDriver->loadMetadataForClass($classMetadata->name, $classMetadata);
     }
 
-    protected function loadDriverForCMSDocuments()
+    protected function loadDriverForCMSDocuments(): AnnotationDriver
     {
         $annotationDriver = $this->loadDriver();
         self::assertInstanceOf(AnnotationDriver::class, $annotationDriver);
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/AbstractMappingDriverTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/AbstractMappingDriverTest.php
index 7ebff8f509..cf3c2f8592 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/AbstractMappingDriverTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/AbstractMappingDriverTest.php
@@ -27,7 +27,7 @@ abstract class AbstractMappingDriverTest extends BaseTest
 {
     abstract protected function loadDriver(): MappingDriver;
 
-    protected function createMetadataDriverImpl()
+    protected function createMetadataDriverImpl(): MappingDriver
     {
         return $this->loadDriver();
     }
@@ -35,7 +35,7 @@ protected function createMetadataDriverImpl()
     /**
      * @doesNotPerformAssertions
      */
-    public function testLoadMapping()
+    public function testLoadMapping(): ClassMetadata
     {
         return $this->dm->getClassMetadata(AbstractMappingDriverUser::class);
     }
@@ -45,7 +45,7 @@ public function testLoadMapping()
      *
      * @depends testLoadMapping
      */
-    public function testDocumentCollectionNameAndInheritance($class)
+    public function testDocumentCollectionNameAndInheritance($class): ClassMetadata
     {
         $this->assertEquals('cms_users', $class->getCollection());
         $this->assertEquals(ClassMetadata::INHERITANCE_TYPE_NONE, $class->inheritanceType);
@@ -58,7 +58,7 @@ public function testDocumentCollectionNameAndInheritance($class)
      *
      * @depends testLoadMapping
      */
-    public function testDocumentMarkedAsReadOnly($class)
+    public function testDocumentMarkedAsReadOnly($class): ClassMetadata
     {
         $this->assertTrue($class->isReadOnly);
 
@@ -70,7 +70,7 @@ public function testDocumentMarkedAsReadOnly($class)
      *
      * @depends testDocumentCollectionNameAndInheritance
      */
-    public function testDocumentLevelReadPreference($class)
+    public function testDocumentLevelReadPreference($class): ClassMetadata
     {
         $this->assertEquals('primaryPreferred', $class->readPreference);
         $this->assertEquals([
@@ -87,7 +87,7 @@ public function testDocumentLevelReadPreference($class)
      *
      * @depends testDocumentCollectionNameAndInheritance
      */
-    public function testDocumentLevelWriteConcern($class)
+    public function testDocumentLevelWriteConcern($class): ClassMetadata
     {
         $this->assertEquals(1, $class->getWriteConcern());
 
@@ -99,7 +99,7 @@ public function testDocumentLevelWriteConcern($class)
      *
      * @depends testDocumentLevelWriteConcern
      */
-    public function testFieldMappings($class)
+    public function testFieldMappings($class): ClassMetadata
     {
         $this->assertCount(14, $class->fieldMappings);
         $this->assertTrue(isset($class->fieldMappings['identifier']));
@@ -117,7 +117,7 @@ public function testFieldMappings($class)
      *
      * @depends testDocumentCollectionNameAndInheritance
      */
-    public function testAssociationMappings($class)
+    public function testAssociationMappings($class): void
     {
         $this->assertCount(6, $class->associationMappings);
         $this->assertTrue(isset($class->associationMappings['address']));
@@ -133,7 +133,7 @@ public function testAssociationMappings($class)
      *
      * @depends testDocumentCollectionNameAndInheritance
      */
-    public function testGetAssociationTargetClass($class)
+    public function testGetAssociationTargetClass($class): void
     {
         $this->assertEquals(Address::class, $class->getAssociationTargetClass('address'));
         $this->assertEquals(Group::class, $class->getAssociationTargetClass('groups'));
@@ -148,7 +148,7 @@ public function testGetAssociationTargetClass($class)
      *
      * @depends testDocumentCollectionNameAndInheritance
      */
-    public function testGetAssociationTargetClassThrowsExceptionWhenEmpty($class)
+    public function testGetAssociationTargetClassThrowsExceptionWhenEmpty($class): void
     {
         $this->expectException(InvalidArgumentException::class);
         $class->getAssociationTargetClass('invalid_association');
@@ -159,7 +159,7 @@ public function testGetAssociationTargetClassThrowsExceptionWhenEmpty($class)
      *
      * @depends testDocumentCollectionNameAndInheritance
      */
-    public function testStringFieldMappings($class)
+    public function testStringFieldMappings($class): ClassMetadata
     {
         $this->assertEquals('string', $class->fieldMappings['name']['type']);
 
@@ -171,7 +171,7 @@ public function testStringFieldMappings($class)
      *
      * @depends testFieldMappings
      */
-    public function testIdentifier($class)
+    public function testIdentifier($class): ClassMetadata
     {
         $this->assertEquals('identifier', $class->identifier);
 
@@ -183,7 +183,7 @@ public function testIdentifier($class)
      *
      * @depends testFieldMappings
      */
-    public function testVersionFieldMappings($class)
+    public function testVersionFieldMappings($class): ClassMetadata
     {
         $this->assertEquals('int', $class->fieldMappings['version']['type']);
         $this->assertNotEmpty($class->fieldMappings['version']['version']);
@@ -196,7 +196,7 @@ public function testVersionFieldMappings($class)
      *
      * @depends testFieldMappings
      */
-    public function testLockFieldMappings($class)
+    public function testLockFieldMappings($class): ClassMetadata
     {
         $this->assertEquals('int', $class->fieldMappings['lock']['type']);
         $this->assertNotEmpty($class->fieldMappings['lock']['lock']);
@@ -209,7 +209,7 @@ public function testLockFieldMappings($class)
      *
      * @depends testIdentifier
      */
-    public function testAssocations($class)
+    public function testAssocations($class): ClassMetadata
     {
         $this->assertCount(14, $class->fieldMappings);
 
@@ -221,7 +221,7 @@ public function testAssocations($class)
      *
      * @depends testAssocations
      */
-    public function testOwningOneToOneAssocation($class)
+    public function testOwningOneToOneAssocation($class): ClassMetadata
     {
         $this->assertTrue(isset($class->fieldMappings['address']));
         $this->assertIsArray($class->fieldMappings['address']);
@@ -240,7 +240,7 @@ public function testOwningOneToOneAssocation($class)
      *
      * @depends testOwningOneToOneAssocation
      */
-    public function testLifecycleCallbacks($class)
+    public function testLifecycleCallbacks($class): ClassMetadata
     {
         $expectedLifecycleCallbacks = [
             'prePersist' => ['doStuffOnPrePersist', 'doOtherStuffOnPrePersistToo'],
@@ -257,7 +257,7 @@ public function testLifecycleCallbacks($class)
      *
      * @depends testLifecycleCallbacks
      */
-    public function testCustomFieldName($class)
+    public function testCustomFieldName($class): ClassMetadata
     {
         $this->assertEquals('name', $class->fieldMappings['name']['fieldName']);
         $this->assertEquals('username', $class->fieldMappings['name']['name']);
@@ -270,7 +270,7 @@ public function testCustomFieldName($class)
      *
      * @depends testCustomFieldName
      */
-    public function testCustomReferenceFieldName($class)
+    public function testCustomReferenceFieldName($class): ClassMetadata
     {
         $this->assertEquals('morePhoneNumbers', $class->fieldMappings['morePhoneNumbers']['fieldName']);
         $this->assertEquals('more_phone_numbers', $class->fieldMappings['morePhoneNumbers']['name']);
@@ -283,7 +283,7 @@ public function testCustomReferenceFieldName($class)
      *
      * @depends testCustomReferenceFieldName
      */
-    public function testCustomEmbedFieldName($class)
+    public function testCustomEmbedFieldName($class): ClassMetadata
     {
         $this->assertEquals('embeddedPhonenumber', $class->fieldMappings['embeddedPhonenumber']['fieldName']);
         $this->assertEquals('embedded_phone_number', $class->fieldMappings['embeddedPhonenumber']['name']);
@@ -296,7 +296,7 @@ public function testCustomEmbedFieldName($class)
      *
      * @depends testCustomEmbedFieldName
      */
-    public function testDiscriminator($class)
+    public function testDiscriminator($class): ClassMetadata
     {
         $this->assertTrue(isset($class->discriminatorField));
         $this->assertTrue(isset($class->discriminatorMap));
@@ -313,7 +313,7 @@ public function testDiscriminator($class)
      *
      * @depends testDiscriminator
      */
-    public function testEmbedDiscriminator($class)
+    public function testEmbedDiscriminator($class): ClassMetadata
     {
         $this->assertTrue(isset($class->fieldMappings['otherPhonenumbers']['discriminatorField']));
         $this->assertTrue(isset($class->fieldMappings['otherPhonenumbers']['discriminatorMap']));
@@ -333,7 +333,7 @@ public function testEmbedDiscriminator($class)
      *
      * @depends testEmbedDiscriminator
      */
-    public function testReferenceDiscriminator($class)
+    public function testReferenceDiscriminator($class): ClassMetadata
     {
         $this->assertTrue(isset($class->fieldMappings['phonenumbers']['discriminatorField']));
         $this->assertTrue(isset($class->fieldMappings['phonenumbers']['discriminatorMap']));
@@ -353,7 +353,7 @@ public function testReferenceDiscriminator($class)
      *
      * @depends testCustomFieldName
      */
-    public function testIndexes($class)
+    public function testIndexes($class): ClassMetadata
     {
         $indexes = $class->indexes;
 
@@ -401,7 +401,7 @@ public function testIndexes($class)
      *
      * @depends testIndexes
      */
-    public function testShardKey($class)
+    public function testShardKey($class): void
     {
         $shardKey = $class->getShardKey();
 
@@ -414,7 +414,7 @@ public function testShardKey($class)
         $this->assertEquals(4096, $shardKey['options']['numInitialChunks'], 'Shard key option has wrong value');
     }
 
-    public function testGridFSMapping()
+    public function testGridFSMapping(): void
     {
         $class = $this->dm->getClassMetadata(AbstractMappingDriverFile::class);
 
@@ -459,7 +459,7 @@ public function testGridFSMapping()
         ], $class->getFieldMapping('metadata'), true);
     }
 
-    public function testGridFSMappingWithCustomRepository()
+    public function testGridFSMappingWithCustomRepository(): void
     {
         $class = $this->dm->getClassMetadata(AbstractMappingDriverFileWithCustomRepository::class);
 
@@ -467,7 +467,7 @@ public function testGridFSMappingWithCustomRepository()
         $this->assertSame(AbstractMappingDriverGridFSRepository::class, $class->customRepositoryClassName);
     }
 
-    public function testDuplicateDatabaseNameInMappingCauseErrors()
+    public function testDuplicateDatabaseNameInMappingCauseErrors(): void
     {
         $this->expectException(MappingException::class);
         $this->expectExceptionMessage(
@@ -477,7 +477,7 @@ public function testDuplicateDatabaseNameInMappingCauseErrors()
         $this->dm->getClassMetadata(AbstractMappingDriverDuplicateDatabaseName::class);
     }
 
-    public function testDuplicateDatabaseNameWithNotSavedDoesNotThrowExeption()
+    public function testDuplicateDatabaseNameWithNotSavedDoesNotThrowExeption(): void
     {
         $metadata = $this->dm->getClassMetadata(AbstractMappingDriverDuplicateDatabaseNameNotSaved::class);
 
@@ -486,7 +486,7 @@ public function testDuplicateDatabaseNameWithNotSavedDoesNotThrowExeption()
         $this->assertTrue($metadata->fieldMappings['bar']['notSaved']);
     }
 
-    public function testViewWithoutRepository()
+    public function testViewWithoutRepository(): void
     {
         $this->expectException(MappingException::class);
         $this->expectExceptionMessage(sprintf(
@@ -499,7 +499,7 @@ public function testViewWithoutRepository()
         $this->dm->getRepository(AbstractMappingDriverViewWithoutRepository::class);
     }
 
-    public function testViewWithWrongRepository()
+    public function testViewWithWrongRepository(): void
     {
         $this->expectException(MappingException::class);
         $this->expectExceptionMessage(sprintf(
@@ -512,7 +512,7 @@ public function testViewWithWrongRepository()
         $this->dm->getRepository(AbstractMappingDriverViewWithWrongRepository::class);
     }
 
-    public function testViewWithoutRootClass()
+    public function testViewWithoutRootClass(): void
     {
         $this->expectException(MappingException::class);
         $this->expectExceptionMessage(sprintf(
@@ -523,7 +523,7 @@ public function testViewWithoutRootClass()
         $this->dm->getClassMetadata(AbstractMappingDriverViewWithoutRootClass::class);
     }
 
-    public function testViewWithNonExistingRootClass()
+    public function testViewWithNonExistingRootClass(): void
     {
         $this->expectException(MappingException::class);
         $this->expectExceptionMessage(sprintf(
@@ -535,7 +535,7 @@ public function testViewWithNonExistingRootClass()
         $this->dm->getClassMetadata(AbstractMappingDriverViewWithNonExistingRootClass::class);
     }
 
-    public function testView()
+    public function testView(): void
     {
         $metadata = $this->dm->getClassMetadata(AbstractMappingDriverView::class);
 
@@ -727,7 +727,7 @@ class AbstractMappingDriverUser
      * @ODM\PrePersist
      */
     #[ODM\PrePersist]
-    public function doStuffOnPrePersist()
+    public function doStuffOnPrePersist(): void
     {
     }
 
@@ -735,7 +735,7 @@ public function doStuffOnPrePersist()
      * @ODM\PrePersist
      */
     #[ODM\PrePersist]
-    public function doOtherStuffOnPrePersistToo()
+    public function doOtherStuffOnPrePersistToo(): void
     {
     }
 
@@ -743,11 +743,11 @@ public function doOtherStuffOnPrePersistToo()
      * @ODM\PostPersist
      */
     #[ODM\PostPersist]
-    public function doStuffOnPostPersist()
+    public function doStuffOnPostPersist(): void
     {
     }
 
-    public static function loadMetadata(ClassMetadata $metadata)
+    public static function loadMetadata(ClassMetadata $metadata): void
     {
         $metadata->setInheritanceType(ClassMetadata::INHERITANCE_TYPE_NONE);
         $metadata->setCollection('cms_users');
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/XmlMappingDriverTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/XmlMappingDriverTest.php
index 54b695665f..c56647474d 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Mapping/XmlMappingDriverTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Mapping/XmlMappingDriverTest.php
@@ -23,7 +23,7 @@ protected function loadDriver(): MappingDriver
         return new XmlDriver(__DIR__ . DIRECTORY_SEPARATOR . 'xml');
     }
 
-    public function testSetShardKeyOptionsByAttributes()
+    public function testSetShardKeyOptionsByAttributes(): void
     {
         $class   = new ClassMetadata(stdClass::class);
         $driver  = $this->loadDriver();
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH297/Address.php b/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH297/Address.php
index d297e9ebb4..bb49082339 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH297/Address.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Tools/GH297/Address.php
@@ -16,7 +16,7 @@ class Address
      */
     private $street;
 
-    public function getStreet()
+    public function getStreet(): ?string
     {
         return $this->street;
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Tools/ResolveTargetDocumentListenerTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Tools/ResolveTargetDocumentListenerTest.php
index fcdd65c8fa..cdc4e48ae0 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Tools/ResolveTargetDocumentListenerTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Tools/ResolveTargetDocumentListenerTest.php
@@ -152,7 +152,7 @@ class TargetDocument implements TargetInterface
      */
     private $id;
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/UnitOfWorkTest.php b/tests/Doctrine/ODM/MongoDB/Tests/UnitOfWorkTest.php
index 7c60cef0cb..f1c5253f06 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/UnitOfWorkTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/UnitOfWorkTest.php
@@ -600,7 +600,7 @@ public function __construct()
         $this->items = new ArrayCollection();
     }
 
-    public function getId()
+    public function getId(): ?int
     {
         return $this->id;
     }
@@ -610,7 +610,7 @@ public function setId($id): void
         $this->id = $id;
     }
 
-    public function getData()
+    public function getData(): ?string
     {
         return $this->data;
     }
@@ -670,7 +670,7 @@ class NotifyChangedRelatedItem
      */
     private $owner;
 
-    public function getId()
+    public function getId(): ?int
     {
         return $this->id;
     }
@@ -680,7 +680,7 @@ public function setId($id): void
         $this->id = $id;
     }
 
-    public function getOwner()
+    public function getOwner(): ?NotifyChangedDocument
     {
         return $this->owner;
     }
diff --git a/tests/Documents/Account.php b/tests/Documents/Account.php
index 18b26885c5..076ee3ada9 100644
--- a/tests/Documents/Account.php
+++ b/tests/Documents/Account.php
@@ -52,11 +52,17 @@ public function getName(): ?string
         return $this->name;
     }
 
+    /**
+     * @param User|CustomUser $user
+     */
     public function setUser($user): void
     {
         $this->user = $user;
     }
 
+    /**
+     * @return CustomUser|User|null
+     */
     public function getUser()
     {
         return $this->user;
diff --git a/tests/Documents/Address.php b/tests/Documents/Address.php
index 6c68db066d..34098d6dc1 100644
--- a/tests/Documents/Address.php
+++ b/tests/Documents/Address.php
@@ -63,12 +63,12 @@ public function setSubAddress(Address $subAddress): void
         $this->subAddress = $subAddress;
     }
 
-    public function getSubAddress()
+    public function getSubAddress(): ?Address
     {
         return $this->subAddress;
     }
 
-    public function getAddress()
+    public function getAddress(): ?string
     {
         return $this->address;
     }
@@ -78,7 +78,7 @@ public function setAddress($address): void
         $this->address = $address;
     }
 
-    public function getCity()
+    public function getCity(): ?string
     {
         return $this->city;
     }
@@ -88,7 +88,7 @@ public function setCity($city): void
         $this->city = $city;
     }
 
-    public function getState()
+    public function getState(): ?string
     {
         return $this->state;
     }
@@ -98,7 +98,7 @@ public function setState($state): void
         $this->state = $state;
     }
 
-    public function getZipcode()
+    public function getZipcode(): ?string
     {
         return $this->zipcode;
     }
diff --git a/tests/Documents/Album.php b/tests/Documents/Album.php
index e3bad20f3a..0c300295cd 100644
--- a/tests/Documents/Album.php
+++ b/tests/Documents/Album.php
@@ -38,7 +38,7 @@ public function __construct($name)
         $this->songs = new ArrayCollection();
     }
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
@@ -48,7 +48,7 @@ public function setName($name): void
         $this->name = $name;
     }
 
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
diff --git a/tests/Documents/Article.php b/tests/Documents/Article.php
index 445fd48421..a3b0b030be 100644
--- a/tests/Documents/Article.php
+++ b/tests/Documents/Article.php
@@ -51,12 +51,12 @@ class Article
      */
     private $tags = [];
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
 
-    public function getTitle()
+    public function getTitle(): ?string
     {
         return $this->title;
     }
@@ -66,21 +66,27 @@ public function setTitle($title): void
         $this->title = $title;
     }
 
-    public function getBody()
+    public function getBody(): ?string
     {
         return $this->body;
     }
 
-    public function setBody($body): void
+    public function setBody(string $body): void
     {
         $this->body = $body;
     }
 
+    /**
+     * @return DateTimeInterface|UTCDateTime|string|null
+     */
     public function getCreatedAt()
     {
         return $this->createdAt;
     }
 
+    /**
+     * @param DateTimeInterface|UTCDateTime|string|null $createdAt
+     */
     public function setCreatedAt($createdAt): void
     {
         $this->createdAt = $createdAt;
diff --git a/tests/Documents/Bars/Bar.php b/tests/Documents/Bars/Bar.php
index a1b67d6920..352f17c17b 100644
--- a/tests/Documents/Bars/Bar.php
+++ b/tests/Documents/Bars/Bar.php
@@ -32,23 +32,23 @@ class Bar
      */
     private $locations;
 
-    public function __construct($name = null)
+    public function __construct(?string $name = null)
     {
         $this->name      = $name;
         $this->locations = new ArrayCollection();
     }
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
 
-    public function setName($name): void
+    public function setName(string $name): void
     {
         $this->name = $name;
     }
 
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
diff --git a/tests/Documents/Bars/Location.php b/tests/Documents/Bars/Location.php
index e64f1ae365..d9c4cffd5c 100644
--- a/tests/Documents/Bars/Location.php
+++ b/tests/Documents/Bars/Location.php
@@ -16,17 +16,17 @@ class Location
      */
     private $name;
 
-    public function __construct($name = null)
+    public function __construct(?string $name = null)
     {
         $this->name = $name;
     }
 
-    public function setName($name): void
+    public function setName(string $name): void
     {
         $this->name = $name;
     }
 
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
diff --git a/tests/Documents/BaseCategory.php b/tests/Documents/BaseCategory.php
index d774ca71d6..5cb905892f 100644
--- a/tests/Documents/BaseCategory.php
+++ b/tests/Documents/BaseCategory.php
@@ -34,7 +34,7 @@ public function setName($name): void
         $this->name = $name;
     }
 
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
diff --git a/tests/Documents/BaseDocument.php b/tests/Documents/BaseDocument.php
index a780e1ecc5..55342d1765 100644
--- a/tests/Documents/BaseDocument.php
+++ b/tests/Documents/BaseDocument.php
@@ -24,7 +24,7 @@ public function setInheritedProperty($value): void
         $this->inheritedProperty = $value;
     }
 
-    public function getInheritedProperty()
+    public function getInheritedProperty(): ?string
     {
         return $this->inheritedProperty;
     }
diff --git a/tests/Documents/BaseEmployee.php b/tests/Documents/BaseEmployee.php
index edbdda92e5..567787b704 100644
--- a/tests/Documents/BaseEmployee.php
+++ b/tests/Documents/BaseEmployee.php
@@ -66,7 +66,7 @@ abstract class BaseEmployee
      */
     protected $address;
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
@@ -102,7 +102,7 @@ public function addNote($note): BaseEmployee
         return $this;
     }
 
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
@@ -114,7 +114,7 @@ public function setName($val): BaseEmployee
         return $this;
     }
 
-    public function getSalary()
+    public function getSalary(): ?float
     {
         return $this->salary;
     }
@@ -126,7 +126,7 @@ public function setSalary($val): BaseEmployee
         return $this;
     }
 
-    public function getStarted()
+    public function getStarted(): ?DateTime
     {
         return $this->started;
     }
@@ -138,7 +138,7 @@ public function setStarted($val): BaseEmployee
         return $this;
     }
 
-    public function getLeft()
+    public function getLeft(): ?DateTime
     {
         return $this->left;
     }
@@ -150,7 +150,7 @@ public function setLeft($val): BaseEmployee
         return $this;
     }
 
-    public function getAddress()
+    public function getAddress(): ?Address
     {
         return $this->address;
     }
diff --git a/tests/Documents/BlogPost.php b/tests/Documents/BlogPost.php
index 6aa0a2b535..956e697189 100644
--- a/tests/Documents/BlogPost.php
+++ b/tests/Documents/BlogPost.php
@@ -113,7 +113,7 @@ public function __construct(?string $name = null)
         $this->name = $name;
     }
 
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
diff --git a/tests/Documents/CmsAddress.php b/tests/Documents/CmsAddress.php
index 1c3802bf43..63f7bb6c30 100644
--- a/tests/Documents/CmsAddress.php
+++ b/tests/Documents/CmsAddress.php
@@ -49,27 +49,27 @@ class CmsAddress
      */
     public $user;
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
 
-    public function getUser()
+    public function getUser(): ?CmsUser
     {
         return $this->user;
     }
 
-    public function getCountry()
+    public function getCountry(): ?string
     {
         return $this->country;
     }
 
-    public function getZipCode()
+    public function getZipCode(): ?string
     {
         return $this->zip;
     }
 
-    public function getCity()
+    public function getCity(): ?string
     {
         return $this->city;
     }
diff --git a/tests/Documents/CmsComment.php b/tests/Documents/CmsComment.php
index a8622611cb..59ed4edade 100644
--- a/tests/Documents/CmsComment.php
+++ b/tests/Documents/CmsComment.php
@@ -61,7 +61,7 @@ public function setArticle(CmsArticle $article): void
         $this->article = $article;
     }
 
-    public function __toString()
+    public function __toString(): string
     {
         return self::class . '[id=' . $this->id . ']';
     }
diff --git a/tests/Documents/CmsUser.php b/tests/Documents/CmsUser.php
index e4f36bba9b..2910195dea 100644
--- a/tests/Documents/CmsUser.php
+++ b/tests/Documents/CmsUser.php
@@ -81,22 +81,22 @@ public function __construct()
         $this->groups       = new ArrayCollection();
     }
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
 
-    public function getStatus()
+    public function getStatus(): ?string
     {
         return $this->status;
     }
 
-    public function getUsername()
+    public function getUsername(): ?string
     {
         return $this->username;
     }
 
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
@@ -145,7 +145,7 @@ public function removePhonenumber($index): bool
         return false;
     }
 
-    public function getAddress()
+    public function getAddress(): CmsAddress
     {
         return $this->address;
     }
diff --git a/tests/Documents/CommentRepository.php b/tests/Documents/CommentRepository.php
index c81d3a4a49..43ecb96fc5 100644
--- a/tests/Documents/CommentRepository.php
+++ b/tests/Documents/CommentRepository.php
@@ -14,6 +14,9 @@
  */
 class CommentRepository extends DocumentRepository
 {
+    /**
+     * @return Comment|false
+     */
     public function findOneComment()
     {
         return $this->getDocumentPersister()
diff --git a/tests/Documents/CustomUser.php b/tests/Documents/CustomUser.php
index c55ab8b25a..ef3e514c16 100644
--- a/tests/Documents/CustomUser.php
+++ b/tests/Documents/CustomUser.php
@@ -37,7 +37,7 @@ class CustomUser
      */
     protected $account;
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
@@ -52,7 +52,7 @@ public function setUsername($username): void
         $this->username = $username;
     }
 
-    public function getUsername()
+    public function getUsername(): ?string
     {
         return $this->username;
     }
@@ -62,7 +62,7 @@ public function setPassword($password): void
         $this->password = $password;
     }
 
-    public function getPassword()
+    public function getPassword(): ?string
     {
         return $this->password;
     }
@@ -73,7 +73,7 @@ public function setAccount(Account $account): void
         $this->account->setUser($this);
     }
 
-    public function getAccount()
+    public function getAccount(): ?Account
     {
         return $this->account;
     }
diff --git a/tests/Documents/Developer.php b/tests/Documents/Developer.php
index 7589e3b3c5..70d2573620 100644
--- a/tests/Documents/Developer.php
+++ b/tests/Documents/Developer.php
@@ -40,12 +40,15 @@ public function __construct(string $name, ?Collection $projects = null)
         $this->projects = $projects ?? new ArrayCollection();
     }
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
 
-    public function getProjects()
+    /**
+     * @return Collection<int, Project>
+     */
+    public function getProjects(): Collection
     {
         return $this->projects;
     }
diff --git a/tests/Documents/Ecommerce/ConfigurableProduct.php b/tests/Documents/Ecommerce/ConfigurableProduct.php
index 70b498349c..325f12a4b5 100644
--- a/tests/Documents/Ecommerce/ConfigurableProduct.php
+++ b/tests/Documents/Ecommerce/ConfigurableProduct.php
@@ -41,24 +41,23 @@ class ConfigurableProduct
     /** @var Option */
     protected $selectedOption;
 
-    public function __construct($name)
+    public function __construct(string $name)
     {
         $this->setName($name);
     }
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
 
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
 
-    public function setName($name): ConfigurableProduct
+    public function setName(string $name): ConfigurableProduct
     {
-        $name = (string) $name;
         if (empty($name)) {
             throw new InvalidArgumentException('Product name cannot be empty');
         }
@@ -68,6 +67,9 @@ public function setName($name): ConfigurableProduct
         return $this;
     }
 
+    /***
+     * @return Collection<int, Option>|array<Option>
+     */
     public function getOptions()
     {
         return $this->options;
@@ -98,12 +100,12 @@ public function addOption($name, ?Money $price = null, ?StockItem $item = null):
         $this->options[] = $name;
     }
 
-    public function getOption($name)
+    public function getOption(string $name): ?Option
     {
         return $this->findOption($name);
     }
 
-    public function removeOption($name): ConfigurableProduct
+    public function removeOption(string $name): ConfigurableProduct
     {
         $option = $this->findOption($name);
         if ($option === null) {
@@ -121,12 +123,12 @@ public function removeOption($name): ConfigurableProduct
         return $this;
     }
 
-    public function hasOption($name): bool
+    public function hasOption(string $name): bool
     {
         return $this->findOption($name) !== null;
     }
 
-    public function selectOption($name): ConfigurableProduct
+    public function selectOption(string $name): ConfigurableProduct
     {
         $option = $this->findOption($name);
         if (! isset($option)) {
@@ -138,7 +140,7 @@ public function selectOption($name): ConfigurableProduct
         return $this;
     }
 
-    protected function findOption($name)
+    protected function findOption(string $name): ?Option
     {
         foreach ($this->options as $option) {
             if ($name === $option->getName()) {
@@ -158,6 +160,9 @@ public function getPrice()
             $this->selectedOption->getPrice() : null;
     }
 
+    /**
+     * @return StockItem[]
+     */
     protected function getStockItems(): array
     {
         return array_map(static function ($option) {
diff --git a/tests/Documents/Ecommerce/Currency.php b/tests/Documents/Ecommerce/Currency.php
index 2f0c5b0d8d..ee7e3d481c 100644
--- a/tests/Documents/Ecommerce/Currency.php
+++ b/tests/Documents/Ecommerce/Currency.php
@@ -36,7 +36,7 @@ class Currency
     /**
      * @ODM\Field(type="float")
      *
-     * @var float|null
+     * @var float
      */
     protected $multiplier;
 
@@ -54,7 +54,7 @@ public function __construct($name, $multiplier = 1)
         $this->setMultiplier($multiplier);
     }
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
@@ -64,7 +64,7 @@ public function getName(): string
         return $this->name;
     }
 
-    public function getMultiplier()
+    public function getMultiplier(): float
     {
         return $this->multiplier;
     }
diff --git a/tests/Documents/Ecommerce/Money.php b/tests/Documents/Ecommerce/Money.php
index 26d213dfa1..9ffdfce988 100644
--- a/tests/Documents/Ecommerce/Money.php
+++ b/tests/Documents/Ecommerce/Money.php
@@ -13,14 +13,14 @@ class Money
     /**
      * @ODM\Field(type="float")
      *
-     * @var float|null
+     * @var float
      */
     protected $amount;
 
     /**
      * @ODM\ReferenceOne(targetDocument=Documents\Ecommerce\Currency::class, cascade="all")
      *
-     * @var Currency|null
+     * @var Currency
      */
     protected $currency;
 
@@ -37,12 +37,12 @@ public function __construct($amount, Currency $currency)
         $this->setCurrency($currency);
     }
 
-    public function getAmount()
+    public function getAmount(): float
     {
         return $this->amount * $this->getCurrency()->getMultiplier();
     }
 
-    public function getCurrency()
+    public function getCurrency(): Currency
     {
         return $this->currency;
     }
diff --git a/tests/Documents/Ecommerce/StockItem.php b/tests/Documents/Ecommerce/StockItem.php
index 3851a67dea..27ca949133 100644
--- a/tests/Documents/Ecommerce/StockItem.php
+++ b/tests/Documents/Ecommerce/StockItem.php
@@ -39,12 +39,12 @@ class StockItem
      */
     private $cost;
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
 
-    public function __construct($name = null, $cost = null, $inventory = null)
+    public function __construct(?string $name = null, ?Money $cost = null, ?int $inventory = null)
     {
         if ($name !== null) {
             $this->setName($name);
@@ -61,14 +61,14 @@ public function __construct($name = null, $cost = null, $inventory = null)
         $this->setInventory($inventory);
     }
 
-    public function setName($name): StockItem
+    public function setName(string $name): StockItem
     {
-        $this->name = (string) $name;
+        $this->name = $name;
 
         return $this;
     }
 
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
@@ -78,7 +78,7 @@ public function setCost(Money $cost): void
         $this->cost = $cost;
     }
 
-    public function getCost()
+    public function getCost(): float
     {
         return $this->cost->getAmount();
     }
@@ -90,7 +90,7 @@ public function setInventory($inventory): StockItem
         return $this;
     }
 
-    public function getInventory()
+    public function getInventory(): ?int
     {
         return $this->inventory;
     }
diff --git a/tests/Documents/Employee.php b/tests/Documents/Employee.php
index f4224a7af6..e944fc302d 100644
--- a/tests/Documents/Employee.php
+++ b/tests/Documents/Employee.php
@@ -16,7 +16,7 @@ class Employee extends BaseEmployee
      */
     private $manager;
 
-    public function getManager()
+    public function getManager(): ?Manager
     {
         return $this->manager;
     }
diff --git a/tests/Documents/Event.php b/tests/Documents/Event.php
index 35f82e5106..f750d3e4fd 100644
--- a/tests/Documents/Event.php
+++ b/tests/Documents/Event.php
@@ -37,7 +37,7 @@ class Event
      */
     private $type;
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
@@ -47,12 +47,12 @@ public function setUser(User $user): void
         $this->user = $user;
     }
 
-    public function getUser()
+    public function getUser(): ?User
     {
         return $this->user;
     }
 
-    public function getTitle()
+    public function getTitle(): ?string
     {
         return $this->title;
     }
@@ -62,7 +62,7 @@ public function setTitle($title): void
         $this->title = $title;
     }
 
-    public function getType()
+    public function getType(): ?string
     {
         return $this->type;
     }
diff --git a/tests/Documents/ForumUser.php b/tests/Documents/ForumUser.php
index b303f0d0c8..ea42aac1fa 100644
--- a/tests/Documents/ForumUser.php
+++ b/tests/Documents/ForumUser.php
@@ -31,17 +31,20 @@ class ForumUser
      */
     public $avatar;
 
+    /**
+     * @return int|ObjectId|null
+     */
     public function getId()
     {
         return $this->id;
     }
 
-    public function getUsername()
+    public function getUsername(): ?string
     {
         return $this->username;
     }
 
-    public function getAvatar()
+    public function getAvatar(): ?ForumAvatar
     {
         return $this->avatar;
     }
diff --git a/tests/Documents/Functional/FavoritesUser.php b/tests/Documents/Functional/FavoritesUser.php
index 757eaa80d6..255e795635 100644
--- a/tests/Documents/Functional/FavoritesUser.php
+++ b/tests/Documents/Functional/FavoritesUser.php
@@ -66,7 +66,7 @@ public function __construct()
         $this->favorites = new ArrayCollection();
     }
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
@@ -76,46 +76,55 @@ public function setFavorite($favorite): void
         $this->favorite = $favorite;
     }
 
-    public function getFavorite()
+    public function getFavorite(): ?object
     {
         return $this->favorite;
     }
 
-    public function setEmbed($embed): void
+    public function setEmbed(object $embed): void
     {
         $this->embed = $embed;
     }
 
-    public function getEmbed()
+    public function getEmbed(): ?object
     {
         return $this->embed;
     }
 
-    public function embed($document): void
+    public function embed(object $document): void
     {
         $this->embedded[] = $document;
     }
 
+    /**
+     * @return Collection<int, object>|array<object>
+     */
     public function getEmbedded()
     {
         return $this->embedded;
     }
 
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
 
-    public function setName($name): void
+    public function setName(string $name): void
     {
         $this->name = $name;
     }
 
+    /**
+     * @param Group|Project $favorite
+     */
     public function addFavorite($favorite): void
     {
         $this->favorites[] = $favorite;
     }
 
+    /**
+     * @return Collection<int, Group|Project>
+     */
     public function getFavorites(): Collection
     {
         return $this->favorites;
diff --git a/tests/Documents/Functional/PreUpdateTestProduct.php b/tests/Documents/Functional/PreUpdateTestProduct.php
index c7b82d3ce5..d749d9de87 100644
--- a/tests/Documents/Functional/PreUpdateTestProduct.php
+++ b/tests/Documents/Functional/PreUpdateTestProduct.php
@@ -32,7 +32,7 @@ class PreUpdateTestProduct
      */
     public $sellable;
 
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
diff --git a/tests/Documents/Functional/PreUpdateTestSeller.php b/tests/Documents/Functional/PreUpdateTestSeller.php
index 35f6e170b6..b867911a55 100644
--- a/tests/Documents/Functional/PreUpdateTestSeller.php
+++ b/tests/Documents/Functional/PreUpdateTestSeller.php
@@ -23,7 +23,7 @@ class PreUpdateTestSeller
      */
     public $name;
 
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
diff --git a/tests/Documents/Functional/VirtualHostDirective.php b/tests/Documents/Functional/VirtualHostDirective.php
index 004fc07c07..c15f666437 100644
--- a/tests/Documents/Functional/VirtualHostDirective.php
+++ b/tests/Documents/Functional/VirtualHostDirective.php
@@ -44,12 +44,12 @@ public function __construct(string $name = '', string $value = '')
         $this->value = $value;
     }
 
-    public function __toString()
+    public function __toString(): string
     {
         return $this->name . ' ' . $this->value;
     }
 
-    public function getRecId()
+    public function getRecId(): ?string
     {
         return $this->recId;
     }
@@ -63,7 +63,7 @@ public function setRecId($value = null): void
         $this->recId = $value;
     }
 
-    public function getName()
+    public function getName(): string
     {
         return $this->name;
     }
@@ -73,7 +73,7 @@ public function setName($value): void
         $this->name = $value;
     }
 
-    public function getValue()
+    public function getValue(): string
     {
         return $this->value;
     }
diff --git a/tests/Documents/Group.php b/tests/Documents/Group.php
index 95f8aa67ac..a35d117bdf 100644
--- a/tests/Documents/Group.php
+++ b/tests/Documents/Group.php
@@ -23,22 +23,22 @@ class Group
      */
     private $name;
 
-    public function __construct($name = null)
+    public function __construct(?string $name = null)
     {
         $this->name = $name;
     }
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
 
-    public function setName($name): void
+    public function setName(string $name): void
     {
         $this->name = $name;
     }
 
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
diff --git a/tests/Documents/Issue.php b/tests/Documents/Issue.php
index ead227b35a..c68675528f 100644
--- a/tests/Documents/Issue.php
+++ b/tests/Documents/Issue.php
@@ -31,12 +31,12 @@ public function __construct($name, $description)
         $this->description = $description;
     }
 
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
 
-    public function getDescription()
+    public function getDescription(): ?string
     {
         return $this->description;
     }
diff --git a/tests/Documents/Message.php b/tests/Documents/Message.php
index 1dd49f0580..3aa5aed0f9 100644
--- a/tests/Documents/Message.php
+++ b/tests/Documents/Message.php
@@ -28,7 +28,7 @@ public function __construct($name)
         $this->name = $name;
     }
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
@@ -38,7 +38,7 @@ public function setName($name): void
         $this->name = $name;
     }
 
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
diff --git a/tests/Documents/Phonebook.php b/tests/Documents/Phonebook.php
index acab031f66..e0d5b6fb8d 100644
--- a/tests/Documents/Phonebook.php
+++ b/tests/Documents/Phonebook.php
@@ -31,7 +31,7 @@ public function __construct(string $title)
         $this->phonenumbers = new ArrayCollection();
     }
 
-    public function getTitle()
+    public function getTitle(): string
     {
         return $this->title;
     }
diff --git a/tests/Documents/Profile.php b/tests/Documents/Profile.php
index 8e07b9a8f6..5dc927b209 100644
--- a/tests/Documents/Profile.php
+++ b/tests/Documents/Profile.php
@@ -5,6 +5,7 @@
 namespace Documents;
 
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
+use MongoDB\BSON\ObjectId;
 
 /** @ODM\Document */
 class Profile
@@ -12,7 +13,7 @@ class Profile
     /**
      * @ODM\Id
      *
-     * @var string|null
+     * @var ObjectId|string|null
      */
     private $profileId;
 
@@ -37,32 +38,35 @@ class Profile
      */
     private $image;
 
-    public function setProfileId($profileId): void
+    public function setProfileId(ObjectId $profileId): void
     {
         $this->profileId = $profileId;
     }
 
+    /**
+     * @return ObjectId|string|null
+     */
     public function getProfileId()
     {
         return $this->profileId;
     }
 
-    public function setFirstName($firstName): void
+    public function setFirstName(string $firstName): void
     {
         $this->firstName = $firstName;
     }
 
-    public function getFirstName()
+    public function getFirstName(): ?string
     {
         return $this->firstName;
     }
 
-    public function setLastName($lastName): void
+    public function setLastName(string $lastName): void
     {
         $this->lastName = $lastName;
     }
 
-    public function getLastName()
+    public function getLastName(): ?string
     {
         return $this->lastName;
     }
@@ -72,7 +76,7 @@ public function setImage(File $image): void
         $this->image = $image;
     }
 
-    public function getImage()
+    public function getImage(): ?File
     {
         return $this->image;
     }
diff --git a/tests/Documents/ProfileNotify.php b/tests/Documents/ProfileNotify.php
index 54439e49f0..90c7e2112c 100644
--- a/tests/Documents/ProfileNotify.php
+++ b/tests/Documents/ProfileNotify.php
@@ -67,7 +67,7 @@ private function propertyChanged($propName, $oldValue, $newValue): void
         }
     }
 
-    public function getProfileId()
+    public function getProfileId(): ?string
     {
         return $this->profileId;
     }
@@ -78,7 +78,7 @@ public function setFirstName($firstName): void
         $this->firstName = $firstName;
     }
 
-    public function getFirstName()
+    public function getFirstName(): ?string
     {
         return $this->firstName;
     }
@@ -89,7 +89,7 @@ public function setLastName($lastName): void
         $this->lastName = $lastName;
     }
 
-    public function getLastName()
+    public function getLastName(): ?string
     {
         return $this->lastName;
     }
@@ -100,7 +100,7 @@ public function setImage(File $image): void
         $this->image = $image;
     }
 
-    public function getImage()
+    public function getImage(): ?File
     {
         return $this->image;
     }
diff --git a/tests/Documents/Project.php b/tests/Documents/Project.php
index 4e2c2b98fa..33f34e3158 100644
--- a/tests/Documents/Project.php
+++ b/tests/Documents/Project.php
@@ -53,7 +53,7 @@ public function __construct(string $name, ?Collection $subProjects = null)
         $this->subProjects = $subProjects ?? new ArrayCollection();
     }
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
diff --git a/tests/Documents/ReferenceUser.php b/tests/Documents/ReferenceUser.php
index 341c3eb7d7..c4a3527e7b 100644
--- a/tests/Documents/ReferenceUser.php
+++ b/tests/Documents/ReferenceUser.php
@@ -4,6 +4,7 @@
 
 namespace Documents;
 
+use Doctrine\Common\Collections\Collection;
 use Doctrine\ODM\MongoDB\Mapping\Annotations as ODM;
 
 /**
@@ -30,7 +31,7 @@ class ReferenceUser
     /**
      * @ODM\ReferenceMany(targetDocument=User::class, storeAs="id")
      *
-     * @var User[]
+     * @var Collection<int, User>|array<User>
      */
     public $users = [];
 
@@ -44,7 +45,7 @@ class ReferenceUser
     /**
      * @ODM\ReferenceMany(targetDocument=User::class, storeAs="dbRef")
      *
-     * @var User[]
+     * @var Collection<int, User>|array<User>
      */
     public $parentUsers = [];
 
@@ -58,7 +59,7 @@ class ReferenceUser
     /**
      * @ODM\ReferenceMany(targetDocument=User::class, storeAs="dbRefWithDb")
      *
-     * @var User[]
+     * @var Collection<int, User>|array<User>
      */
     public $otherUsers = [];
 
@@ -72,14 +73,14 @@ class ReferenceUser
     /**
      * @ODM\ReferenceMany(targetDocument=User::class, storeAs="ref")
      *
-     * @var User[]
+     * @var Collection<int, User>|array<User>
      */
     public $referencedUsers = [];
 
     /**
      * @ODM\EmbedMany(targetDocument=Documents\IndirectlyReferencedUser::class)
      *
-     * @var IndirectlyReferencedUser[]
+     * @var Collection<int, IndirectlyReferencedUser>|array<IndirectlyReferencedUser>
      */
     public $indirectlyReferencedUsers = [];
 
@@ -106,7 +107,7 @@ public function addUser(User $user): void
     }
 
     /**
-     * @return User[]
+     * @return Collection<int, User>|array<User>
      */
     public function getUsers()
     {
@@ -129,7 +130,7 @@ public function addParentUser(User $parentUser): void
     }
 
     /**
-     * @return User[]
+     * @return Collection<int, User>|array<User>
      */
     public function getParentUsers()
     {
@@ -152,7 +153,7 @@ public function addOtherUser(User $otherUser): void
     }
 
     /**
-     * @return User[]
+     * @return Collection<int, User>|array<User>
      */
     public function getOtherUsers()
     {
@@ -175,7 +176,7 @@ public function addReferencedUser(User $referencedUser): void
     }
 
     /**
-     * @return User[]
+     * @return Collection<int, User>|array<User>
      */
     public function getReferencedUsers()
     {
diff --git a/tests/Documents/SimpleReferenceUser.php b/tests/Documents/SimpleReferenceUser.php
index 41f55ed21b..39cc6a54c0 100644
--- a/tests/Documents/SimpleReferenceUser.php
+++ b/tests/Documents/SimpleReferenceUser.php
@@ -55,17 +55,20 @@ public function addUser(User $user): void
         $this->users[] = $user;
     }
 
+    /**
+     * @return Collection<int, User>|array<User>
+     */
     public function getUsers()
     {
         return $this->users;
     }
 
-    public function setName($name): void
+    public function setName(string $name): void
     {
         $this->name = $name;
     }
 
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
diff --git a/tests/Documents/Song.php b/tests/Documents/Song.php
index 950d18a448..154c39b2f5 100644
--- a/tests/Documents/Song.php
+++ b/tests/Documents/Song.php
@@ -26,7 +26,7 @@ public function setName($name): void
         $this->name = $name;
     }
 
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
diff --git a/tests/Documents/Task.php b/tests/Documents/Task.php
index 8a8bbd3baf..ed70f70685 100644
--- a/tests/Documents/Task.php
+++ b/tests/Documents/Task.php
@@ -28,7 +28,7 @@ public function __construct($name)
         $this->name = $name;
     }
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
@@ -38,7 +38,7 @@ public function setName($name): void
         $this->name = $name;
     }
 
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
diff --git a/tests/Documents/Tournament/Tournament.php b/tests/Documents/Tournament/Tournament.php
index 8f74f89f51..728fdc8518 100644
--- a/tests/Documents/Tournament/Tournament.php
+++ b/tests/Documents/Tournament/Tournament.php
@@ -40,7 +40,7 @@ public function __construct($name)
         $this->name = $name;
     }
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
@@ -50,7 +50,7 @@ public function setName($name): void
         $this->name = $name;
     }
 
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
diff --git a/tests/Documents/User.php b/tests/Documents/User.php
index 3091c58663..68f5aeb7b8 100644
--- a/tests/Documents/User.php
+++ b/tests/Documents/User.php
@@ -90,7 +90,7 @@ class User extends BaseDocument
     /**
      * @ODM\ReferenceMany(targetDocument=Group::class, cascade={"all"})
      *
-     * @var Collection<int, Group>
+     * @var Collection<int, Group>|array<Group>
      */
     protected $groups;
 
@@ -259,7 +259,7 @@ public function log($log): void
         $this->logs[] = $log;
     }
 
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
@@ -269,7 +269,7 @@ public function setUsername($username): void
         $this->username = $username;
     }
 
-    public function getUsername()
+    public function getUsername(): ?string
     {
         return $this->username;
     }
@@ -279,7 +279,7 @@ public function setPassword($password): void
         $this->password = $password;
     }
 
-    public function getPassword()
+    public function getPassword(): ?string
     {
         return $this->password;
     }
@@ -294,7 +294,7 @@ public function getCreatedAt(): DateTime
         return $this->createdAt;
     }
 
-    public function getAddress()
+    public function getAddress(): ?Address
     {
         return $this->address;
     }
@@ -316,7 +316,7 @@ public function setProfile(Profile $profile): void
         $this->profile = $profile;
     }
 
-    public function getProfile()
+    public function getProfile(): ?Profile
     {
         return $this->profile;
     }
@@ -337,7 +337,7 @@ public function setAccount(Account $account): void
         $this->account->setUser($this);
     }
 
-    public function getAccount()
+    public function getAccount(): ?Account
     {
         return $this->account;
     }
@@ -348,7 +348,7 @@ public function setAccountSimple(Account $account): void
         $this->accountSimple->setUser($this);
     }
 
-    public function getAccountSimple()
+    public function getAccountSimple(): ?Account
     {
         return $this->accountSimple;
     }
@@ -366,21 +366,33 @@ public function addPhonenumber(Phonenumber $phonenumber): void
         $this->phonenumbers[] = $phonenumber;
     }
 
+    /**
+     * @return Collection<int, Group>
+     */
     public function getSortedAscGroups(): Collection
     {
         return $this->sortedAscGroups;
     }
 
+    /**
+     * @return Collection<int, Group>
+     */
     public function getSortedDescGroups(): Collection
     {
         return $this->sortedDescGroups;
     }
 
+    /**
+     * @return Collection<int, Group>|array<Group>
+     */
     public function getGroups()
     {
         return $this->groups;
     }
 
+    /**
+     * @param Collection<int, Group>|array<Group> $groups
+     */
     public function setGroups($groups): void
     {
         $this->groups = $groups;
@@ -391,7 +403,7 @@ public function addGroup(Group $group): void
         $this->groups[] = $group;
     }
 
-    public function removeGroup($name): bool
+    public function removeGroup(string $name): bool
     {
         foreach ($this->groups as $key => $group) {
             if ($group->getName() === $name) {
@@ -409,7 +421,10 @@ public function addGroupSimple(Group $group): void
         $this->groupsSimple[] = $group;
     }
 
-    public function getUniqueGroups()
+    /**
+     * @return Collection<int, Group>
+     */
+    public function getUniqueGroups(): Collection
     {
         return $this->uniqueGroups;
     }
@@ -434,7 +449,7 @@ public function setHits($hits): void
         $this->hits = $hits;
     }
 
-    public function getCount()
+    public function getCount(): ?int
     {
         return $this->count;
     }
@@ -444,7 +459,7 @@ public function setCount($count): void
         $this->count = $count;
     }
 
-    public function getFloatCount()
+    public function getFloatCount(): ?float
     {
         return $this->floatCount;
     }
@@ -454,7 +469,7 @@ public function setFloatCount($floatCount): void
         $this->floatCount = $floatCount;
     }
 
-    public function getDecimal128Count()
+    public function getDecimal128Count(): ?string
     {
         return $this->decimal128Count;
     }
@@ -464,16 +479,22 @@ public function setDecimal128Count($decimal128Count): void
         $this->decimal128Count = $decimal128Count;
     }
 
-    public function getSimpleReferenceOneInverse()
+    public function getSimpleReferenceOneInverse(): ?SimpleReferenceUser
     {
         return $this->simpleReferenceOneInverse;
     }
 
-    public function getSimpleReferenceManyInverse()
+    /**
+     * @return Collection<int, SimpleReferenceUser>
+     */
+    public function getSimpleReferenceManyInverse(): Collection
     {
         return $this->simpleReferenceManyInverse;
     }
 
+    /**
+     * @param float|int|null $num
+     */
     public function incrementCount($num = null): void
     {
         if ($num === null) {
@@ -483,6 +504,9 @@ public function incrementCount($num = null): void
         }
     }
 
+    /**
+     * @param float|int|null $num
+     */
     public function incrementFloatCount($num = null): void
     {
         if ($num === null) {
@@ -492,12 +516,15 @@ public function incrementFloatCount($num = null): void
         }
     }
 
-    public function incrementDecimal128Count($num = null): void
+    public function incrementDecimal128Count(?string $num = null): void
     {
         $this->decimal128Count = bcadd($this->decimal128Count, $num ?? '1');
     }
 
-    public function setPosts($posts): void
+    /**
+     * @param Collection<int, BlogPost> $posts
+     */
+    public function setPosts(Collection $posts): void
     {
         $this->posts = $posts;
     }
@@ -507,7 +534,7 @@ public function addPost(BlogPost $post): void
         $this->posts[] = $post;
     }
 
-    public function removePost($id): bool
+    public function removePost(string $id): bool
     {
         foreach ($this->posts as $key => $post) {
             if ($post->id === $id) {
@@ -520,12 +547,18 @@ public function removePost($id): bool
         return false;
     }
 
+    /**
+     * @return Collection<int, BlogPost>
+     */
     public function getPosts(): Collection
     {
         return $this->posts;
     }
 
-    public function setPhonenumbers($phonenumbers): void
+    /**
+     * @param Collection<int, Phonenumber> $phonenumbers
+     */
+    public function setPhonenumbers(Collection $phonenumbers): void
     {
         $this->phonenumbers = $phonenumbers;
     }
@@ -535,6 +568,9 @@ public function addPhonebook(Phonebook $phonebook): void
         $this->phonebooks->add($phonebook);
     }
 
+    /**
+     * @return Collection<int, Phonebook>
+     */
     public function getPhonebooks(): Collection
     {
         return $this->phonebooks;
diff --git a/tests/Documents/VersionedUser.php b/tests/Documents/VersionedUser.php
index c61143ab28..72d3397fe5 100644
--- a/tests/Documents/VersionedUser.php
+++ b/tests/Documents/VersionedUser.php
@@ -20,7 +20,7 @@ class VersionedUser extends User
      */
     protected $version;
 
-    public function getVersion()
+    public function getVersion(): ?int
     {
         return $this->version;
     }
diff --git a/tools/sandbox/Documents/Account.php b/tools/sandbox/Documents/Account.php
index 1479f0b4c8..cf05e2e1e3 100644
--- a/tools/sandbox/Documents/Account.php
+++ b/tools/sandbox/Documents/Account.php
@@ -43,7 +43,7 @@ public function getName(): string
         return $this->name;
     }
 
-    public function __toString()
+    public function __toString(): string
     {
         return $this->name;
     }
diff --git a/tools/sandbox/Documents/Phonenumber.php b/tools/sandbox/Documents/Phonenumber.php
index a6abbfcf62..0f0618fd8a 100644
--- a/tools/sandbox/Documents/Phonenumber.php
+++ b/tools/sandbox/Documents/Phonenumber.php
@@ -31,7 +31,7 @@ public function getPhonenumber(): ?string
         return $this->phonenumber;
     }
 
-    public function __toString()
+    public function __toString(): string
     {
         return (string) $this->phonenumber;
     }
diff --git a/tools/sandbox/Documents/User.php b/tools/sandbox/Documents/User.php
index a42ddf5635..f29ef169b4 100644
--- a/tools/sandbox/Documents/User.php
+++ b/tools/sandbox/Documents/User.php
@@ -118,7 +118,7 @@ public function getPhonenumbers(): Collection
         return $this->phonenumbers;
     }
 
-    public function __toString()
+    public function __toString(): string
     {
         return (string) $this->username;
     }