diff --git a/cli-config.doctrine_dbal.php.dist b/cli-config.doctrine_dbal.php.dist
index 7d66902a8..1c68c8a7b 100644
--- a/cli-config.doctrine_dbal.php.dist
+++ b/cli-config.doctrine_dbal.php.dist
@@ -7,16 +7,17 @@
  * Add instances of commands for eventual implementation specific commands to this array.
  */
 
-$extraCommands = array();
+$extraCommands = [];
 $extraCommands[] = new \Jackalope\Tools\Console\Command\InitDoctrineDbalCommand();
 
-$params = array(
+$params = [
     'driver'    => 'pdo_mysql',
     'host'      => '127.0.0.1',
     'user'      => 'root',
     'password'  => '',
     'dbname'    => 'phpcr_odm_tests',
-);
+    'charset'   => 'utf8mb4',
+];
 
 $dbConn = \Doctrine\DBAL\DriverManager::getConnection($params);
 
@@ -31,7 +32,7 @@ if (isset($argv[1])
     && $argv[1] != 'help'
 ) {
     $factory = new \Jackalope\RepositoryFactoryDoctrineDBAL();
-    $repository = $factory->getRepository(array('jackalope.doctrine_dbal_connection' => $dbConn));
+    $repository = $factory->getRepository(['jackalope.doctrine_dbal_connection' => $dbConn]);
     $credentials = new \PHPCR\SimpleCredentials(null, null);
     $session = $repository->login($credentials, $workspace);
 
@@ -44,11 +45,11 @@ if (isset($argv[1])
 
     $dm = \Doctrine\ODM\PHPCR\DocumentManager::create($session, $config);
 
-    $helperSet = new \Symfony\Component\Console\Helper\HelperSet(array(
+    $helperSet = new \Symfony\Component\Console\Helper\HelperSet([
         'phpcr' => new \PHPCR\Util\Console\Helper\PhpcrHelper($session),
         'phpcr_console_dumper' => new \PHPCR\Util\Console\Helper\PhpcrConsoleDumperHelper(),
         'dm' => new \Doctrine\ODM\PHPCR\Tools\Console\Helper\DocumentManagerHelper(null, $dm),
-    ));
+    ]);
 
     if (class_exists('Symfony\Component\Console\Helper\QuestionHelper')) {
         $helperSet->set(new \Symfony\Component\Console\Helper\QuestionHelper(), 'question');
@@ -57,7 +58,7 @@ if (isset($argv[1])
     }
 } elseif (isset($argv[1]) && $argv[1] == 'jackalope:init:dbal') {
     // special case: the init command needs the db connection, but a session is impossible if the db is not yet initialized
-    $helperSet = new \Symfony\Component\Console\Helper\HelperSet(array(
+    $helperSet = new \Symfony\Component\Console\Helper\HelperSet([
         'connection' => new \Jackalope\Tools\Console\Helper\DoctrineDbalHelper($dbConn)
-    ));
+    ]);
 }
diff --git a/cli-config.jackrabbit.php.dist b/cli-config.jackrabbit.php.dist
index 85876f9d5..5be8bda18 100644
--- a/cli-config.jackrabbit.php.dist
+++ b/cli-config.jackrabbit.php.dist
@@ -7,7 +7,7 @@
  * Add instances of commands for eventual implementation specific commands to this array.
  */
 
-$extraCommands = array();
+$extraCommands = [];
 $extraCommands[] = new \Jackalope\Tools\Console\Command\JackrabbitCommand();
 
 if (! isset($argv[1])
@@ -19,9 +19,9 @@ if (! isset($argv[1])
     return;
 }
 
-$params = array(
+$params = [
     'jackalope.jackrabbit_uri'  => 'http://127.0.0.1:8080/server/',
-);
+];
 
 $workspace = 'default';
 $user = 'admin';
@@ -42,11 +42,11 @@ $config->setMetadataDriverImpl($driver);
 
 $dm = \Doctrine\ODM\PHPCR\DocumentManager::create($session, $config);
 
-$helperSet = new \Symfony\Component\Console\Helper\HelperSet(array(
+$helperSet = new \Symfony\Component\Console\Helper\HelperSet([
     'phpcr' => new \PHPCR\Util\Console\Helper\PhpcrHelper($session),
     'phpcr_console_dumper' => new \PHPCR\Util\Console\Helper\PhpcrConsoleDumperHelper(),
     'dm' => new \Doctrine\ODM\PHPCR\Tools\Console\Helper\DocumentManagerHelper(null, $dm),
-));
+]);
 
 if (class_exists('Symfony\Component\Console\Helper\QuestionHelper')) {
     $helperSet->set(new \Symfony\Component\Console\Helper\QuestionHelper(), 'question');
diff --git a/docs/en/cookbook/custom_documentclass_mapper.rst b/docs/en/cookbook/custom_documentclass_mapper.rst
index 36340a4d3..bb4d67892 100644
--- a/docs/en/cookbook/custom_documentclass_mapper.rst
+++ b/docs/en/cookbook/custom_documentclass_mapper.rst
@@ -62,9 +62,9 @@ custom mapper::
 
     /* prepare the doctrine configuration */
     $config = new \Doctrine\ODM\PHPCR\Configuration();
-    $map = array(
+    $map = [
         'standard-templating-kit:pages/stkSection' => \Sandbox\MagnoliaBundle\Document\Section::class,
-    );
+    ];
     $mapper = new MagnoliaDocumentClassMapper($map);
     $config->setDocumentClassMapper($mapper);
 
@@ -125,18 +125,18 @@ of instantiating the default one. An example from the `symfony cmf sandbox`_
 
         $container
             ->register('doctrine.odm_configuration', '%doctrine_phpcr.odm.configuration.class%')
-            ->addMethodCall('setDocumentClassMapper', array(
+            ->addMethodCall('setDocumentClassMapper', [
                 new Reference('sandbox_magnolia.odm_mapper'),
-            ))
+            ])
         ;
 
         $container ->setDefinition('sandbox_amgnolia.odm_mapper', new Definition(
             MagnoliaDocumentClassMapper::class,
-            array(
-                array(
+            [
+                [
                     'standard-templating-kit:pages/stkSection' => Section::class,
-                ),
-            ),
+                ],
+            ],
         ));
 
 .. _`symfony cmf sandbox`: https://github.com/symfony-cmf/cmf-sandbox/tree/magnolia_integration
diff --git a/docs/en/reference/installation-configuration.rst b/docs/en/reference/installation-configuration.rst
index 7c366ddd6..13af2e3cd 100644
--- a/docs/en/reference/installation-configuration.rst
+++ b/docs/en/reference/installation-configuration.rst
@@ -82,6 +82,7 @@ Bootstrap will roughly look like this when using mysql as storage backend::
         'user'      => $user,
         'password'  => $pass,
         'dbname'    => 'phpcr_odm_tutorial',
+        'charset'   => 'utf8mb4', // only when using MySQL
     ];
 
     // Bootstrap Doctrine DBAL
@@ -253,6 +254,7 @@ A complete configuration could look like this::
         'user'      => $user,
         'password'  => $pass,
         'dbname'    => 'phpcr_odm_tutorial',
+        'charset'   => 'utf8mb4',
     ];
     $dbConn = \Doctrine\DBAL\DriverManager::getConnection($params);
     $parameters = ['jackalope.doctrine_dbal_connection' => $dbConn];
diff --git a/docs/en/reference/introduction.rst b/docs/en/reference/introduction.rst
index fcf7117f9..cc70ea9ad 100644
--- a/docs/en/reference/introduction.rst
+++ b/docs/en/reference/introduction.rst
@@ -100,6 +100,7 @@ your project root directory::
         'user'      => 'root',
         'password'  => '',
         'dbname'    => 'phpcr_odm_tutorial',
+        'charset'   => 'utf8mb4',
     ];
 
     $workspace = 'default';
diff --git a/lib/Doctrine/ODM/PHPCR/ChildrenCollection.php b/lib/Doctrine/ODM/PHPCR/ChildrenCollection.php
index 427f64883..4afdcd56c 100644
--- a/lib/Doctrine/ODM/PHPCR/ChildrenCollection.php
+++ b/lib/Doctrine/ODM/PHPCR/ChildrenCollection.php
@@ -36,7 +36,7 @@ class ChildrenCollection extends PersistentCollection
      * @param int               $fetchDepth Optional fetch depth, -1 to not override
      * @param string|null       $locale     The locale to use during the loading of this collection
      */
-    public function __construct(DocumentManagerInterface $dm, object $document, array|string $filter = null, int $fetchDepth = -1, string $locale = null)
+    public function __construct(DocumentManagerInterface $dm, object $document, array|string|null $filter = null, int $fetchDepth = -1, ?string $locale = null)
     {
         parent::__construct($dm);
         $this->document = $document;
diff --git a/lib/Doctrine/ODM/PHPCR/Decorator/DocumentManagerDecorator.php b/lib/Doctrine/ODM/PHPCR/Decorator/DocumentManagerDecorator.php
index 65346c171..ea5de65ff 100644
--- a/lib/Doctrine/ODM/PHPCR/Decorator/DocumentManagerDecorator.php
+++ b/lib/Doctrine/ODM/PHPCR/Decorator/DocumentManagerDecorator.php
@@ -133,7 +133,7 @@ public function createPhpcrQueryBuilder(): PhpcrQueryBuilder
         return $this->wrapped->createPhpcrQueryBuilder();
     }
 
-    public function getDocumentsByPhpcrQuery(QueryInterface $query, string $className = null, string $primarySelector = null): Collection
+    public function getDocumentsByPhpcrQuery(QueryInterface $query, ?string $className = null, ?string $primarySelector = null): Collection
     {
         return $this->wrapped->getDocumentsByPhpcrQuery($query, $className, $primarySelector);
     }
@@ -168,17 +168,17 @@ public function reorder(object $document, string $srcName, string $targetName, b
         $this->wrapped->reorder($document, $srcName, $targetName, $before);
     }
 
-    public function getChildren(object $document, array|string $filter = null, int $fetchDepth = -1, string $locale = null): ChildrenCollection
+    public function getChildren(object $document, array|string|null $filter = null, int $fetchDepth = -1, ?string $locale = null): ChildrenCollection
     {
         return $this->wrapped->getChildren($document, $filter, $fetchDepth, $locale);
     }
 
-    public function getReferrers(object $document, string $type = null, string $name = null, string $locale = null, string $refClass = null): ReferrersCollection
+    public function getReferrers(object $document, ?string $type = null, ?string $name = null, ?string $locale = null, ?string $refClass = null): ReferrersCollection
     {
         return $this->wrapped->getReferrers($document, $type, $name, $locale, $refClass);
     }
 
-    public function flush(object|array $document = null): void
+    public function flush(object|array|null $document = null): void
     {
         $this->wrapped->flush($document);
     }
diff --git a/lib/Doctrine/ODM/PHPCR/DocumentClassMapper.php b/lib/Doctrine/ODM/PHPCR/DocumentClassMapper.php
index fe07d7b93..b72765abb 100644
--- a/lib/Doctrine/ODM/PHPCR/DocumentClassMapper.php
+++ b/lib/Doctrine/ODM/PHPCR/DocumentClassMapper.php
@@ -13,7 +13,7 @@
  */
 class DocumentClassMapper implements DocumentClassMapperInterface
 {
-    private function expandClassName(DocumentManagerInterface $dm, string $className = null): ?string
+    private function expandClassName(DocumentManagerInterface $dm, ?string $className = null): ?string
     {
         if (null === $className) {
             return null;
@@ -26,7 +26,7 @@ private function expandClassName(DocumentManagerInterface $dm, string $className
         return $className;
     }
 
-    public function getClassName(DocumentManagerInterface $dm, NodeInterface $node, string $className = null): string
+    public function getClassName(DocumentManagerInterface $dm, NodeInterface $node, ?string $className = null): string
     {
         $className = $this->expandClassName($dm, $className);
 
diff --git a/lib/Doctrine/ODM/PHPCR/DocumentClassMapperInterface.php b/lib/Doctrine/ODM/PHPCR/DocumentClassMapperInterface.php
index 32688edcb..3a9e5dcc3 100644
--- a/lib/Doctrine/ODM/PHPCR/DocumentClassMapperInterface.php
+++ b/lib/Doctrine/ODM/PHPCR/DocumentClassMapperInterface.php
@@ -20,7 +20,7 @@ interface DocumentClassMapperInterface
      * @throws ClassMismatchException if $node represents a class that is not
      *                                a descendant of $className
      */
-    public function getClassName(DocumentManagerInterface $dm, NodeInterface $node, string $className = null): string;
+    public function getClassName(DocumentManagerInterface $dm, NodeInterface $node, ?string $className = null): string;
 
     /**
      * Write any relevant meta data into the node to be able to map back to a class name later.
diff --git a/lib/Doctrine/ODM/PHPCR/DocumentManager.php b/lib/Doctrine/ODM/PHPCR/DocumentManager.php
index 8dc0953e1..18d9001fd 100644
--- a/lib/Doctrine/ODM/PHPCR/DocumentManager.php
+++ b/lib/Doctrine/ODM/PHPCR/DocumentManager.php
@@ -61,7 +61,7 @@ class DocumentManager implements DocumentManagerInterface
     private LocaleChooserInterface $localeChooserStrategy;
     private ValueConverter $valueConverter;
 
-    public function __construct(SessionInterface $session, Configuration $config = null, EventManager $evm = null)
+    public function __construct(SessionInterface $session, ?Configuration $config = null, ?EventManager $evm = null)
     {
         $this->session = $session;
         $this->config = $config ?: new Configuration();
@@ -136,7 +136,7 @@ public function getPhpcrSession(): SessionInterface
     /**
      * Factory method to create a Document Manager.
      */
-    public static function create(SessionInterface $session, Configuration $config = null, EventManager $evm = null): DocumentManager
+    public static function create(SessionInterface $session, ?Configuration $config = null, ?EventManager $evm = null): DocumentManager
     {
         return new self($session, $config, $evm);
     }
@@ -342,7 +342,7 @@ public function createPhpcrQueryBuilder(): PhpcrQueryBuilder
         return new PhpcrQueryBuilder($qm->getQOMFactory());
     }
 
-    public function getDocumentsByPhpcrQuery(QueryInterface $query, string $className = null, string $primarySelector = null): Collection
+    public function getDocumentsByPhpcrQuery(QueryInterface $query, ?string $className = null, ?string $primarySelector = null): Collection
     {
         $this->errorIfClosed();
 
@@ -504,14 +504,14 @@ public function refresh($document): void
         $this->unitOfWork->refresh($document);
     }
 
-    public function getChildren(object $document, array|string $filter = null, int $fetchDepth = -1, string $locale = null): ChildrenCollection
+    public function getChildren(object $document, array|string|null $filter = null, int $fetchDepth = -1, ?string $locale = null): ChildrenCollection
     {
         $this->errorIfClosed();
 
         return new ChildrenCollection($this, $document, $filter, $fetchDepth, $locale);
     }
 
-    public function getReferrers(object $document, string $type = null, string $name = null, string $locale = null, $refClass = null): ReferrersCollection
+    public function getReferrers(object $document, ?string $type = null, ?string $name = null, ?string $locale = null, $refClass = null): ReferrersCollection
     {
         $this->errorIfClosed();
 
@@ -530,7 +530,7 @@ public function getReferrers(object $document, string $type = null, string $name
      * @throws InvalidArgumentException if $document is neither null nor a
      *                                  document or an array of documents
      */
-    public function flush(object|array $document = null): void
+    public function flush(object|array|null $document = null): void
     {
         if (null !== $document && !is_object($document) && !is_array($document)) {
             throw new InvalidArgumentException('Parameter $document needs to be an object, '.gettype($document).' given');
diff --git a/lib/Doctrine/ODM/PHPCR/DocumentManagerInterface.php b/lib/Doctrine/ODM/PHPCR/DocumentManagerInterface.php
index d960882c0..34192d5c3 100644
--- a/lib/Doctrine/ODM/PHPCR/DocumentManagerInterface.php
+++ b/lib/Doctrine/ODM/PHPCR/DocumentManagerInterface.php
@@ -236,7 +236,7 @@ public function createPhpcrQueryBuilder(): PhpcrQueryBuilder;
      * @param string|null    $className       document class
      * @param string|null    $primarySelector name of the selector for the document to return in case of a join query
      */
-    public function getDocumentsByPhpcrQuery(QueryInterface $query, string $className = null, string $primarySelector = null): Collection;
+    public function getDocumentsByPhpcrQuery(QueryInterface $query, ?string $className = null, ?string $primarySelector = null): Collection;
 
     /**
      * Bind the translatable fields of the document in the specified locale.
@@ -331,7 +331,7 @@ public function reorder(object $document, string $srcName, string $targetName, b
      *
      * @throws InvalidArgumentException if $document is not an object
      */
-    public function getChildren(object $document, array|string $filter = null, int $fetchDepth = -1, string $locale = null): ChildrenCollection;
+    public function getChildren(object $document, array|string|null $filter = null, int $fetchDepth = -1, ?string $locale = null): ChildrenCollection;
 
     /**
      * Get the documents that refer a given document using an optional name.
@@ -353,7 +353,7 @@ public function getChildren(object $document, array|string $filter = null, int $
      *
      * @throws InvalidArgumentException if $document is not an object
      */
-    public function getReferrers(object $document, string $type = null, string $name = null, string $locale = null, string $refClass = null): ReferrersCollection;
+    public function getReferrers(object $document, ?string $type = null, ?string $name = null, ?string $locale = null, ?string $refClass = null): ReferrersCollection;
 
     /**
      * Gets a reference to the document identified by the given type and identifier
@@ -480,7 +480,7 @@ public function getUnitOfWork(): UnitOfWork;
      * @throws InvalidArgumentException if $document is neither null nor a
      *                                  document or an array of documents
      */
-    public function flush(object|array $document = null): void;
+    public function flush(object|array|null $document = null): void;
 
     /**
      * Closes the DocumentManager. All entities that are currently managed
diff --git a/lib/Doctrine/ODM/PHPCR/DocumentRepository.php b/lib/Doctrine/ODM/PHPCR/DocumentRepository.php
index 584f18117..cb0b8e428 100644
--- a/lib/Doctrine/ODM/PHPCR/DocumentRepository.php
+++ b/lib/Doctrine/ODM/PHPCR/DocumentRepository.php
@@ -81,7 +81,7 @@ public function findAll(): Collection
      *
      * @return Collection the objects matching the criteria
      */
-    public function findBy(array $criteria, array $orderBy = null, int $limit = null, int $offset = null): Collection
+    public function findBy(array $criteria, ?array $orderBy = null, ?int $limit = null, ?int $offset = null): Collection
     {
         $qb = $this->createQueryBuilder('a');
 
@@ -199,7 +199,7 @@ public function getClassMetadata(): ClassMetadata
      *
      * @see \PHPCR\PropertyType
      */
-    public function quote(string $val, int $type = null): string
+    public function quote(string $val, ?int $type = null): string
     {
         return $this->dm->quote($val, $type);
     }
diff --git a/lib/Doctrine/ODM/PHPCR/Id/AssignedIdGenerator.php b/lib/Doctrine/ODM/PHPCR/Id/AssignedIdGenerator.php
index 8c73aef4b..8216265f3 100644
--- a/lib/Doctrine/ODM/PHPCR/Id/AssignedIdGenerator.php
+++ b/lib/Doctrine/ODM/PHPCR/Id/AssignedIdGenerator.php
@@ -15,7 +15,7 @@ class AssignedIdGenerator extends IdGenerator
      *
      * {@inheritdoc}
      */
-    public function generate(object $document, ClassMetadata $class, DocumentManagerInterface $dm, object $parent = null): string
+    public function generate(object $document, ClassMetadata $class, DocumentManagerInterface $dm, ?object $parent = null): string
     {
         if (!$class->identifier || !$id = $class->getFieldValue($document, $class->identifier)) {
             throw new IdException('ID could not be read from the document instance using the AssignedIdGenerator.');
diff --git a/lib/Doctrine/ODM/PHPCR/Id/AutoIdGenerator.php b/lib/Doctrine/ODM/PHPCR/Id/AutoIdGenerator.php
index 9dbffb774..9912cfd42 100644
--- a/lib/Doctrine/ODM/PHPCR/Id/AutoIdGenerator.php
+++ b/lib/Doctrine/ODM/PHPCR/Id/AutoIdGenerator.php
@@ -17,7 +17,7 @@ class AutoIdGenerator extends ParentIdGenerator
      *
      * {@inheritdoc}
      */
-    public function generate(object $document, ClassMetadata $class, DocumentManagerInterface $dm, object $parent = null): string
+    public function generate(object $document, ClassMetadata $class, DocumentManagerInterface $dm, ?object $parent = null): string
     {
         if (null === $parent) {
             $parent = $class->parentMapping ? $class->getFieldValue($document, $class->parentMapping) : null;
diff --git a/lib/Doctrine/ODM/PHPCR/Id/IdException.php b/lib/Doctrine/ODM/PHPCR/Id/IdException.php
index a852d043a..952d2b3c1 100644
--- a/lib/Doctrine/ODM/PHPCR/Id/IdException.php
+++ b/lib/Doctrine/ODM/PHPCR/Id/IdException.php
@@ -55,7 +55,7 @@ public static function parentIdCouldNotBeDetermined(object $document, string $pa
         return new self($message);
     }
 
-    public static function illegalName(object $document, string $fieldName, string $nodeName, \Throwable $previous = null): self
+    public static function illegalName(object $document, string $fieldName, string $nodeName, ?\Throwable $previous = null): self
     {
         $message = sprintf(
             'Nodename property "%s" of document "%s" contains the illegal PHPCR value "%s".',
diff --git a/lib/Doctrine/ODM/PHPCR/Id/IdGenerator.php b/lib/Doctrine/ODM/PHPCR/Id/IdGenerator.php
index ec2dc5bd5..7f06922e8 100644
--- a/lib/Doctrine/ODM/PHPCR/Id/IdGenerator.php
+++ b/lib/Doctrine/ODM/PHPCR/Id/IdGenerator.php
@@ -44,5 +44,5 @@ public static function create(int $generatorType): IdGenerator
     /**
      * Generate the actual id, to be overwritten by extending classes.
      */
-    abstract public function generate(object $document, ClassMetadata $class, DocumentManagerInterface $dm, object $parent = null): string;
+    abstract public function generate(object $document, ClassMetadata $class, DocumentManagerInterface $dm, ?object $parent = null): string;
 }
diff --git a/lib/Doctrine/ODM/PHPCR/Id/ParentIdGenerator.php b/lib/Doctrine/ODM/PHPCR/Id/ParentIdGenerator.php
index 73c6034bd..baaef0e06 100644
--- a/lib/Doctrine/ODM/PHPCR/Id/ParentIdGenerator.php
+++ b/lib/Doctrine/ODM/PHPCR/Id/ParentIdGenerator.php
@@ -16,7 +16,7 @@ class ParentIdGenerator extends IdGenerator
      *
      * {@inheritdoc}
      */
-    public function generate(object $document, ClassMetadata $class, DocumentManagerInterface $dm, object $parent = null): string
+    public function generate(object $document, ClassMetadata $class, DocumentManagerInterface $dm, ?object $parent = null): string
     {
         if (null === $parent) {
             $parent = $class->parentMapping ? $class->getFieldValue($document, $class->parentMapping) : null;
diff --git a/lib/Doctrine/ODM/PHPCR/Id/RepositoryIdGenerator.php b/lib/Doctrine/ODM/PHPCR/Id/RepositoryIdGenerator.php
index 790636a31..9566f628c 100644
--- a/lib/Doctrine/ODM/PHPCR/Id/RepositoryIdGenerator.php
+++ b/lib/Doctrine/ODM/PHPCR/Id/RepositoryIdGenerator.php
@@ -13,7 +13,7 @@ class RepositoryIdGenerator extends IdGenerator
      *
      * {@inheritdoc}
      */
-    public function generate(object $document, ClassMetadata $class, DocumentManagerInterface $dm, object $parent = null): string
+    public function generate(object $document, ClassMetadata $class, DocumentManagerInterface $dm, ?object $parent = null): string
     {
         if (null === $parent) {
             $parent = $class->parentMapping ? $class->getFieldValue($document, $class->parentMapping) : null;
diff --git a/lib/Doctrine/ODM/PHPCR/Id/RepositoryIdInterface.php b/lib/Doctrine/ODM/PHPCR/Id/RepositoryIdInterface.php
index 0d97da1e9..ecb996058 100644
--- a/lib/Doctrine/ODM/PHPCR/Id/RepositoryIdInterface.php
+++ b/lib/Doctrine/ODM/PHPCR/Id/RepositoryIdInterface.php
@@ -7,5 +7,5 @@
  */
 interface RepositoryIdInterface
 {
-    public function generateId(object $document, object $parent = null): string;
+    public function generateId(object $document, ?object $parent = null): string;
 }
diff --git a/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Child.php b/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Child.php
index 3524eb36a..e838fe125 100644
--- a/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Child.php
+++ b/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Child.php
@@ -7,14 +7,14 @@
 #[\Attribute(\Attribute::TARGET_PROPERTY)]
 final class Child implements MappingAttribute
 {
-    public array|null $cascade;
+    public ?array $cascade;
 
     /**
      * @param string[]|string $cascade
      */
     public function __construct(
-        public null|string $nodeName = null,
-        array|string $cascade = null,
+        public ?string $nodeName = null,
+        array|string|null $cascade = null,
     ) {
         $this->cascade = null === $cascade ? null : (array) $cascade;
     }
diff --git a/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Children.php b/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Children.php
index 7202a55a6..82840a2b9 100644
--- a/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Children.php
+++ b/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Children.php
@@ -7,18 +7,18 @@
 #[\Attribute(\Attribute::TARGET_PROPERTY)]
 final class Children implements MappingAttribute
 {
-    public array|null $filter;
-    public array|null $cascade;
+    public ?array $filter;
+    public ?array $cascade;
 
     /**
      * @param string[]|string $filter
      * @param string[]|string $cascade
      */
     public function __construct(
-        array|string $filter = null,
+        array|string|null $filter = null,
         public int $fetchDepth = -1,
         public bool $ignoreUntranslated = true,
-        array|string $cascade = null,
+        array|string|null $cascade = null,
     ) {
         $this->filter = null === $filter ? null : (array) $filter;
         $this->cascade = null === $cascade ? null : (array) $cascade;
diff --git a/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Document.php b/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Document.php
index 08d79ae12..5952e0b9c 100644
--- a/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Document.php
+++ b/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Document.php
@@ -7,20 +7,20 @@
 #[\Attribute(\Attribute::TARGET_CLASS)]
 class Document implements MappingAttribute
 {
-    public array|null $mixins;
-    public array|null $childClasses;
+    public ?array $mixins;
+    public ?array $childClasses;
 
     public function __construct(
-        public null|string $nodeType = null,
-        public null|string $repositoryClass = null,
-        public null|string $translator = null,
-        string|array $mixins = null,
-        public bool|null $inheritMixins = null,
-        public null|string $versionable = null,
-        public null|bool $referenceable = null,
-        public null|bool $uniqueNodeType = null,
-        string|array $childClasses = null,
-        public bool|null $isLeaf = null,
+        public ?string $nodeType = null,
+        public ?string $repositoryClass = null,
+        public ?string $translator = null,
+        string|array|null $mixins = null,
+        public ?bool $inheritMixins = null,
+        public ?string $versionable = null,
+        public ?bool $referenceable = null,
+        public ?bool $uniqueNodeType = null,
+        string|array|null $childClasses = null,
+        public ?bool $isLeaf = null,
     ) {
         $this->mixins = null === $mixins ? null : (array) $mixins;
         $this->childClasses = null === $childClasses ? null : (array) $childClasses;
diff --git a/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Field.php b/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Field.php
index c2b31b45c..ce9d30583 100644
--- a/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Field.php
+++ b/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Field.php
@@ -8,10 +8,10 @@
 class Field implements MappingAttribute
 {
     public function __construct(
-        public null|string $property = null,
+        public ?string $property = null,
         public string $type = 'undefined',
         public bool $multivalue = false,
-        public null|string $assoc = null,
+        public ?string $assoc = null,
         public bool $nullable = false,
         public bool $translated = false,
     ) {
diff --git a/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Id.php b/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Id.php
index db48afcbb..7052597a9 100644
--- a/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Id.php
+++ b/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Id.php
@@ -10,7 +10,7 @@ final class Id implements MappingAttribute
     public function __construct(
         public bool $id = true,
         public string $type = 'string',
-        public null|string $strategy = null,
+        public ?string $strategy = null,
     ) {
     }
 }
diff --git a/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/MixedReferrers.php b/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/MixedReferrers.php
index 4ec5371a5..b91029af2 100644
--- a/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/MixedReferrers.php
+++ b/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/MixedReferrers.php
@@ -8,7 +8,7 @@
 final class MixedReferrers implements MappingAttribute
 {
     public function __construct(
-        public null|string $referenceType = null
+        public ?string $referenceType = null
     ) {
     }
 }
diff --git a/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/ParentDocument.php b/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/ParentDocument.php
index a2e9d25c5..f0c0ab7cd 100644
--- a/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/ParentDocument.php
+++ b/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/ParentDocument.php
@@ -12,10 +12,10 @@
 #[\Attribute(\Attribute::TARGET_PROPERTY)]
 final class ParentDocument implements MappingAttribute
 {
-    public array|null $cascade;
+    public ?array $cascade;
 
     public function __construct(
-        string|array $cascade = null
+        string|array|null $cascade = null
     ) {
         $this->cascade = null === $cascade ? null : (array) $cascade;
     }
diff --git a/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Reference.php b/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Reference.php
index 6b011b877..e5619958f 100644
--- a/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Reference.php
+++ b/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Reference.php
@@ -6,7 +6,7 @@
 
 abstract class Reference implements MappingAttribute
 {
-    public array|null $cascade;
+    public ?array $cascade;
 
     /**
      * @param string[]|string $cascade
@@ -15,10 +15,10 @@ public function __construct(
         /**
          * The PHPCR property name to use.
          */
-        public null|string $property = null,
-        public null|string $targetDocument = null,
+        public ?string $property = null,
+        public ?string $targetDocument = null,
         public string $strategy = 'weak',
-        array|string $cascade = null
+        array|string|null $cascade = null
     ) {
         $this->cascade = null === $cascade ? null : (array) $cascade;
     }
diff --git a/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Referrers.php b/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Referrers.php
index 04d2d2f33..9b8bdd921 100644
--- a/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Referrers.php
+++ b/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Referrers.php
@@ -7,7 +7,7 @@
 #[\Attribute(\Attribute::TARGET_PROPERTY)]
 final class Referrers implements MappingAttribute
 {
-    public array|null $cascade;
+    public ?array $cascade;
 
     /**
      * @param string[]|string $cascade
@@ -15,7 +15,7 @@ final class Referrers implements MappingAttribute
     public function __construct(
         public string $referencedBy,
         public string $referringDocument,
-        array|string $cascade = null
+        array|string|null $cascade = null
     ) {
         $this->cascade = null === $cascade ? null : (array) $cascade;
     }
diff --git a/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Uuid.php b/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Uuid.php
index 9a16e8891..5e9d9832a 100644
--- a/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Uuid.php
+++ b/lib/Doctrine/ODM/PHPCR/Mapping/Attributes/Uuid.php
@@ -9,7 +9,7 @@ public function __construct(
         string $property = 'jcr:uuid',
         string $type = 'string',
         bool $multivalue = false,
-        string $assoc = null,
+        ?string $assoc = null,
         bool $nullable = false,
     ) {
         parent::__construct($property, $type, $multivalue, $assoc, $nullable, false);
diff --git a/lib/Doctrine/ODM/PHPCR/Mapping/ClassMetadata.php b/lib/Doctrine/ODM/PHPCR/Mapping/ClassMetadata.php
index 11f8c29d3..df152de10 100644
--- a/lib/Doctrine/ODM/PHPCR/Mapping/ClassMetadata.php
+++ b/lib/Doctrine/ODM/PHPCR/Mapping/ClassMetadata.php
@@ -680,7 +680,7 @@ public function getNamespace(): string
         return $this->namespace;
     }
 
-    public function mapId(array $mapping, self $inherited = null): void
+    public function mapId(array $mapping, ?self $inherited = null): void
     {
         if (true === ($mapping['id'] ?? false)) {
             $mapping['type'] = 'string';
@@ -693,21 +693,21 @@ public function mapId(array $mapping, self $inherited = null): void
         $this->validateAndCompleteFieldMapping($mapping, $inherited, false, false);
     }
 
-    public function mapNode(array $mapping, self $inherited = null): void
+    public function mapNode(array $mapping, ?self $inherited = null): void
     {
         $mapping['type'] = 'node';
         $this->validateAndCompleteFieldMapping($mapping, $inherited, false);
         $this->node = $mapping['fieldName'];
     }
 
-    public function mapNodename(array $mapping, self $inherited = null): void
+    public function mapNodename(array $mapping, ?self $inherited = null): void
     {
         $mapping['type'] = 'nodename';
         $this->validateAndCompleteFieldMapping($mapping, $inherited, false, false);
         $this->nodename = $mapping['fieldName'];
     }
 
-    public function mapParentDocument(array $mapping, self $inherited = null): void
+    public function mapParentDocument(array $mapping, ?self $inherited = null): void
     {
         if (empty($mapping['cascade'])) {
             $mapping['cascade'] = 0;
@@ -717,7 +717,7 @@ public function mapParentDocument(array $mapping, self $inherited = null): void
         $this->parentMapping = $mapping['fieldName'];
     }
 
-    public function mapChild(array $mapping, self $inherited = null): void
+    public function mapChild(array $mapping, ?self $inherited = null): void
     {
         if (empty($mapping['cascade'])) {
             $mapping['cascade'] = 0;
@@ -730,7 +730,7 @@ public function mapChild(array $mapping, self $inherited = null): void
         $this->childMappings[$mapping['fieldName']] = $mapping['fieldName'];
     }
 
-    public function mapChildren(array $mapping, self $inherited = null): void
+    public function mapChildren(array $mapping, ?self $inherited = null): void
     {
         if (empty($mapping['cascade'])) {
             $mapping['cascade'] = 0;
@@ -749,7 +749,7 @@ public function mapChildren(array $mapping, self $inherited = null): void
         $this->childrenMappings[$mapping['fieldName']] = $mapping['fieldName'];
     }
 
-    public function mapReferrers(array $mapping, self $inherited = null): void
+    public function mapReferrers(array $mapping, ?self $inherited = null): void
     {
         if (empty($mapping['referencedBy'])) {
             throw MappingException::referrerWithoutReferencedBy($this->name, $mapping['fieldName']);
@@ -772,7 +772,7 @@ public function mapReferrers(array $mapping, self $inherited = null): void
         $this->referrersMappings[$mapping['fieldName']] = $mapping['fieldName'];
     }
 
-    public function mapMixedReferrers(array $mapping, self $inherited = null): void
+    public function mapMixedReferrers(array $mapping, ?self $inherited = null): void
     {
         if (!(array_key_exists('referenceType', $mapping) && in_array($mapping['referenceType'], [null, 'weak', 'hard'], true))) {
             throw new MappingException(sprintf(
@@ -797,28 +797,28 @@ public function mapMixedReferrers(array $mapping, self $inherited = null): void
         $this->mixedReferrersMappings[$mapping['fieldName']] = $mapping['fieldName'];
     }
 
-    public function mapLocale(array $mapping, self $inherited = null): void
+    public function mapLocale(array $mapping, ?self $inherited = null): void
     {
         $mapping['type'] = 'locale';
         $mapping = $this->validateAndCompleteFieldMapping($mapping, $inherited, false, false);
         $this->localeMapping = $mapping['fieldName'];
     }
 
-    public function mapDepth(array $mapping, self $inherited = null): void
+    public function mapDepth(array $mapping, ?self $inherited = null): void
     {
         $mapping['type'] = 'depth';
         $mapping = $this->validateAndCompleteFieldMapping($mapping, $inherited, false, false);
         $this->depthMapping = $mapping['fieldName'];
     }
 
-    public function mapVersionName(array $mapping, self $inherited = null): void
+    public function mapVersionName(array $mapping, ?self $inherited = null): void
     {
         $mapping['type'] = 'versionname';
         $mapping = $this->validateAndCompleteFieldMapping($mapping, $inherited, false, false);
         $this->versionNameField = $mapping['fieldName'];
     }
 
-    public function mapVersionCreated(array $mapping, self $inherited = null): void
+    public function mapVersionCreated(array $mapping, ?self $inherited = null): void
     {
         $mapping['type'] = 'versioncreated';
         $mapping = $this->validateAndCompleteFieldMapping($mapping, $inherited, false, false);
@@ -837,7 +837,7 @@ public function mapLifecycleCallbacks(array $mapping): void
      *
      * @throws MappingException
      */
-    private function validateAndCompleteFieldMapping(array $mapping, self $inherited = null, bool $isField = true, $phpcrLabel = 'property'): array
+    private function validateAndCompleteFieldMapping(array $mapping, ?self $inherited = null, bool $isField = true, $phpcrLabel = 'property'): array
     {
         if ($inherited) {
             if (!array_key_exists('inherited', $mapping)) {
@@ -916,7 +916,7 @@ private function validateAndCompleteFieldMapping(array $mapping, self $inherited
         return $mapping;
     }
 
-    private function validateAndCompleteAssociationMapping(array $mapping, self $inherited = null, bool|string $phpcrLabel = 'property'): array
+    private function validateAndCompleteAssociationMapping(array $mapping, ?self $inherited = null, bool|string $phpcrLabel = 'property'): array
     {
         $mapping = $this->validateAndCompleteFieldMapping($mapping, $inherited, false, $phpcrLabel);
         if ($inherited) {
@@ -1063,14 +1063,14 @@ private function determineIdStrategy(): void
         ));
     }
 
-    public function mapManyToOne(array $mapping, self $inherited = null): void
+    public function mapManyToOne(array $mapping, ?self $inherited = null): void
     {
         $mapping['type'] = self::MANY_TO_ONE;
         $mapping = $this->validateAndCompleteAssociationMapping($mapping, $inherited);
         $this->referenceMappings[$mapping['fieldName']] = $mapping['fieldName'];
     }
 
-    public function mapManyToMany(array $mapping, self $inherited = null): void
+    public function mapManyToMany(array $mapping, ?self $inherited = null): void
     {
         $mapping['type'] = self::MANY_TO_MANY;
         $mapping = $this->validateAndCompleteAssociationMapping($mapping, $inherited);
@@ -1360,7 +1360,7 @@ public function isNullable(string $fieldName): bool
      *
      * @param array $mapping the mapping information
      */
-    public function mapField(array $mapping, self $inherited = null): void
+    public function mapField(array $mapping, ?self $inherited = null): void
     {
         $parentMapping = array_key_exists('fieldName', $mapping) && array_key_exists($mapping['fieldName'], $this->mappings)
             ? $this->mappings[$mapping['fieldName']]
@@ -1629,7 +1629,7 @@ public function getFieldMapping(string $fieldName): array
      *
      * @param mixed[]|null $arguments the arguments to pass to the callback
      */
-    public function invokeLifecycleCallbacks(string $lifecycleEvent, object $document, array $arguments = null): void
+    public function invokeLifecycleCallbacks(string $lifecycleEvent, object $document, ?array $arguments = null): void
     {
         foreach ($this->lifecycleCallbacks[$lifecycleEvent] as $callback) {
             if (null !== $arguments) {
diff --git a/lib/Doctrine/ODM/PHPCR/Mapping/Driver/AttributeDriver.php b/lib/Doctrine/ODM/PHPCR/Mapping/Driver/AttributeDriver.php
index 1a6832d81..b7d169ca1 100644
--- a/lib/Doctrine/ODM/PHPCR/Mapping/Driver/AttributeDriver.php
+++ b/lib/Doctrine/ODM/PHPCR/Mapping/Driver/AttributeDriver.php
@@ -82,12 +82,12 @@ public function loadMetadataForClass($className, PersistenceClassMetadata $metad
         $classAttributes = $this->reader->getClassAttributes($reflectionClass);
 
         // Evaluate document attribute
-        if (array_key_exists(ODM\Document::class, $classAttributes)) {
-            $documentAttribute = $classAttributes[ODM\Document::class];
-            \assert($documentAttribute instanceof ODM\Document);
-        } elseif (isset($classAttributes[ODM\MappedSuperclass::class])) {
-            $documentAttribute = $classAttributes[ODM\MappedSuperclass::class];
-            \assert($documentAttribute instanceof ODM\MappedSuperclass);
+        if (array_key_exists(Document::class, $classAttributes)) {
+            $documentAttribute = $classAttributes[Document::class];
+            \assert($documentAttribute instanceof Document);
+        } elseif (isset($classAttributes[MappedSuperclass::class])) {
+            $documentAttribute = $classAttributes[MappedSuperclass::class];
+            \assert($documentAttribute instanceof MappedSuperclass);
             $metadata->isMappedSuperclass = true;
         } else {
             throw MappingException::classIsNotAValidDocument($className);
diff --git a/lib/Doctrine/ODM/PHPCR/Mapping/MappingException.php b/lib/Doctrine/ODM/PHPCR/Mapping/MappingException.php
index 8c1ff5b82..ffcd97a0f 100644
--- a/lib/Doctrine/ODM/PHPCR/Mapping/MappingException.php
+++ b/lib/Doctrine/ODM/PHPCR/Mapping/MappingException.php
@@ -32,7 +32,7 @@ public static function classHasNoField(string $documentClass, string $fieldName)
         return new self("Invalid mapping: The class '$documentClass' does not have a field named '$fieldName'");
     }
 
-    public static function illegalChildName(string $documentClass, string $fieldName, string $nodeName, \Throwable $previous = null): self
+    public static function illegalChildName(string $documentClass, string $fieldName, string $nodeName, ?\Throwable $previous = null): self
     {
         return new self("Invalid mapping: The field '$fieldName' of '$documentClass' is configured to the illegal PHPCR node name '$nodeName'.", 0, $previous);
     }
diff --git a/lib/Doctrine/ODM/PHPCR/PersistentCollection.php b/lib/Doctrine/ODM/PHPCR/PersistentCollection.php
index b5a48287a..312e53596 100644
--- a/lib/Doctrine/ODM/PHPCR/PersistentCollection.php
+++ b/lib/Doctrine/ODM/PHPCR/PersistentCollection.php
@@ -186,7 +186,7 @@ public function isEmpty(): bool
         return $this->collection->isEmpty();
     }
 
-    public function key(): int|null|string
+    public function key(): int|string|null
     {
         $this->initialize();
 
diff --git a/lib/Doctrine/ODM/PHPCR/Proxy/ProxyFactory.php b/lib/Doctrine/ODM/PHPCR/Proxy/ProxyFactory.php
index e60d0ee65..77f820a33 100644
--- a/lib/Doctrine/ODM/PHPCR/Proxy/ProxyFactory.php
+++ b/lib/Doctrine/ODM/PHPCR/Proxy/ProxyFactory.php
@@ -139,7 +139,7 @@ private function createInitializer(PhpcrClassMetadata $classMetadata): \Closure
      *
      * @throws UnexpectedValueException
      */
-    private function createCloner(PhpcrClassMetadata $classMetadata, \ReflectionProperty $reflectionId = null): \Closure
+    private function createCloner(PhpcrClassMetadata $classMetadata, ?\ReflectionProperty $reflectionId = null): \Closure
     {
         $className = $classMetadata->getName();
         $documentManager = $this->documentManager;
diff --git a/lib/Doctrine/ODM/PHPCR/Query/Builder/AbstractNode.php b/lib/Doctrine/ODM/PHPCR/Query/Builder/AbstractNode.php
index 777ce3b30..24377767f 100644
--- a/lib/Doctrine/ODM/PHPCR/Query/Builder/AbstractNode.php
+++ b/lib/Doctrine/ODM/PHPCR/Query/Builder/AbstractNode.php
@@ -64,7 +64,7 @@ abstract class AbstractNode
 
     private ?AbstractNode $parent;
 
-    public function __construct(AbstractNode $parent = null)
+    public function __construct(?AbstractNode $parent = null)
     {
         $this->parent = $parent;
     }
diff --git a/lib/Doctrine/ODM/PHPCR/Query/Builder/ConverterBase.php b/lib/Doctrine/ODM/PHPCR/Query/Builder/ConverterBase.php
index 6e8874bb0..6411e35f6 100644
--- a/lib/Doctrine/ODM/PHPCR/Query/Builder/ConverterBase.php
+++ b/lib/Doctrine/ODM/PHPCR/Query/Builder/ConverterBase.php
@@ -3,7 +3,6 @@
 namespace Doctrine\ODM\PHPCR\Query\Builder;
 
 use Doctrine\ODM\PHPCR\Exception\InvalidArgumentException;
-use Doctrine\ODM\PHPCR\Query\Builder\AbstractNode as QBConstants;
 use PHPCR\Query\QOM\BindVariableValueInterface;
 use PHPCR\Query\QOM\ChildNodeInterface;
 use PHPCR\Query\QOM\ChildNodeJoinConditionInterface;
@@ -234,11 +233,11 @@ public function walkWhereOr(WhereOr $whereOr): ConstraintInterface
 
     protected function walkSourceJoin(SourceJoin $node): JoinInterface
     {
-        $left = $this->dispatch($node->getChildOfType(QBConstants::NT_SOURCE_JOIN_LEFT));
+        $left = $this->dispatch($node->getChildOfType(AbstractNode::NT_SOURCE_JOIN_LEFT));
         \assert($left instanceof SourceInterface);
-        $right = $this->dispatch($node->getChildOfType(QBConstants::NT_SOURCE_JOIN_RIGHT));
+        $right = $this->dispatch($node->getChildOfType(AbstractNode::NT_SOURCE_JOIN_RIGHT));
         \assert($right instanceof SourceInterface);
-        $cond = $this->dispatch($node->getChildOfType(QBConstants::NT_SOURCE_JOIN_CONDITION_FACTORY));
+        $cond = $this->dispatch($node->getChildOfType(AbstractNode::NT_SOURCE_JOIN_CONDITION_FACTORY));
         \assert($cond instanceof JoinConditionInterface);
 
         return $this->qomf()->join($left, $right, $node->getJoinType(), $cond);
@@ -391,10 +390,10 @@ protected function walkConstraintChild(ConstraintChild $node): ChildNodeInterfac
     protected function walkConstraintComparison(ConstraintComparison $node): ComparisonInterface
     {
         $dynOp = $node->getChildOfType(
-            QBConstants::NT_OPERAND_DYNAMIC
+            AbstractNode::NT_OPERAND_DYNAMIC
         );
         $statOp = $node->getChildOfType(
-            QBConstants::NT_OPERAND_STATIC
+            AbstractNode::NT_OPERAND_STATIC
         );
 
         $phpcrDynOp = $this->dispatch($dynOp);
@@ -412,7 +411,7 @@ protected function walkConstraintComparison(ConstraintComparison $node): Compari
     protected function walkConstraintNot(ConstraintNot $node): ConstraintInterface
     {
         $con = $node->getChildOfType(
-            QBConstants::NT_CONSTRAINT
+            AbstractNode::NT_CONSTRAINT
         );
 
         $phpcrCon = $this->dispatch($con);
@@ -464,7 +463,7 @@ protected function walkOperandDynamicName(OperandDynamicName $node): NodeNameInt
     protected function walkOperandDynamicLowerCase(OperandDynamicLowerCase $node): LowerCaseInterface
     {
         $child = $node->getChildOfType(
-            QBConstants::NT_OPERAND_DYNAMIC
+            AbstractNode::NT_OPERAND_DYNAMIC
         );
 
         $phpcrChild = $this->dispatch($child);
@@ -478,7 +477,7 @@ protected function walkOperandDynamicLowerCase(OperandDynamicLowerCase $node): L
     protected function walkOperandDynamicUpperCase(OperandDynamicUpperCase $node): UpperCaseInterface
     {
         $child = $node->getChildOfType(
-            QBConstants::NT_OPERAND_DYNAMIC
+            AbstractNode::NT_OPERAND_DYNAMIC
         );
 
         $phpcrChild = $this->dispatch($child);
@@ -513,7 +512,7 @@ protected function walkOrderBy(OrderBy $node): array
         foreach ($orderings as $ordering) {
             \assert($ordering instanceof Ordering);
             $dynOp = $ordering->getChildOfType(
-                QBConstants::NT_OPERAND_DYNAMIC
+                AbstractNode::NT_OPERAND_DYNAMIC
             );
 
             $phpcrDynOp = $this->dispatch($dynOp);
diff --git a/lib/Doctrine/ODM/PHPCR/Query/Builder/ConverterPhpcr.php b/lib/Doctrine/ODM/PHPCR/Query/Builder/ConverterPhpcr.php
index 144864d34..75480f8f0 100644
--- a/lib/Doctrine/ODM/PHPCR/Query/Builder/ConverterPhpcr.php
+++ b/lib/Doctrine/ODM/PHPCR/Query/Builder/ConverterPhpcr.php
@@ -56,7 +56,7 @@ class ConverterPhpcr extends ConverterBase
      * Used to keep track of which sources are used with translated fields, to
      * tell the translation strategy to update if needed.
      *
-     * @var array<string, boolean> keys are the alias, value is true
+     * @var array<string, bool> keys are the alias, value is true
      */
     private array $aliasWithTranslatedFields;
 
@@ -290,7 +290,7 @@ protected function walkOperandStaticLiteral(OperandStaticLiteral $node): Literal
     {
         $value = $node->getValue();
 
-        if ($field = $node->getParent()?->getChildOfType(AbstractNode::NT_OPERAND_DYNAMIC)) {
+        if ($field = $node->getParent()?->getChildOfType(QBConstants::NT_OPERAND_DYNAMIC)) {
             if ($field instanceof OperandDynamicField) {
                 $meta = $this->aliasMetadata[$field->getAlias()];
                 $fieldMapping = $meta->getFieldMapping($field->getField());
diff --git a/lib/Doctrine/ODM/PHPCR/Query/Builder/QueryBuilder.php b/lib/Doctrine/ODM/PHPCR/Query/Builder/QueryBuilder.php
index 7ae48abe6..fff396332 100644
--- a/lib/Doctrine/ODM/PHPCR/Query/Builder/QueryBuilder.php
+++ b/lib/Doctrine/ODM/PHPCR/Query/Builder/QueryBuilder.php
@@ -28,7 +28,7 @@
  *
  * @author Daniel Leech <daniel@dantleech.com>
  */
-class QueryBuilder extends AbstractNode
+class QueryBuilder extends QBConstants
 {
     private ?ConverterInterface $converter = null;
     private int $firstResult = 0;
@@ -156,7 +156,7 @@ public function orWhere($void = null): WhereOr
      *
      * @factoryMethod From
      */
-    public function from(string $primaryAlias = null): From
+    public function from(?string $primaryAlias = null): From
     {
         $this->primaryAlias = $primaryAlias;
 
diff --git a/lib/Doctrine/ODM/PHPCR/Query/Query.php b/lib/Doctrine/ODM/PHPCR/Query/Query.php
index 09ea27499..d29bad155 100644
--- a/lib/Doctrine/ODM/PHPCR/Query/Query.php
+++ b/lib/Doctrine/ODM/PHPCR/Query/Query.php
@@ -124,7 +124,7 @@ public function setDocumentClass(string $documentClass): self
      *
      * @throws QueryException if $hydrationMode is not known
      */
-    public function execute(array $parameters = null, int $hydrationMode = null)
+    public function execute(?array $parameters = null, ?int $hydrationMode = null)
     {
         if (!empty($parameters)) {
             $this->setParameters($parameters);
@@ -195,7 +195,7 @@ public function getPhpcrNodeResult()
      *
      * @throws QueryException if more than one result found
      */
-    public function getOneOrNullResult(int $hydrationMode = null)
+    public function getOneOrNullResult(?int $hydrationMode = null)
     {
         $result = $this->execute(null, $hydrationMode);
 
@@ -219,7 +219,7 @@ public function getOneOrNullResult(int $hydrationMode = null)
      *
      * @throws QueryException if no result or more than one result found
      */
-    public function getSingleResult(int $hydrationMode = null)
+    public function getSingleResult(?int $hydrationMode = null)
     {
         $result = $this->getOneOrNullResult($hydrationMode);
 
diff --git a/lib/Doctrine/ODM/PHPCR/ReferenceManyCollection.php b/lib/Doctrine/ODM/PHPCR/ReferenceManyCollection.php
index 72eb84cd4..12172b07f 100644
--- a/lib/Doctrine/ODM/PHPCR/ReferenceManyCollection.php
+++ b/lib/Doctrine/ODM/PHPCR/ReferenceManyCollection.php
@@ -33,7 +33,7 @@ class ReferenceManyCollection extends PersistentCollection
      * @param string|null              $locale          The locale to use during the loading of this collection
      * @param string                   $referenceType   Identifiers used for reference nodes in this collection, either path or default uuid
      */
-    public function __construct(DocumentManagerInterface $dm, object $document, string $property, array $referencedNodes, ?string $targetDocument, string $locale = null, string $referenceType = self::REFERENCE_TYPE_UUID)
+    public function __construct(DocumentManagerInterface $dm, object $document, string $property, array $referencedNodes, ?string $targetDocument, ?string $locale = null, string $referenceType = self::REFERENCE_TYPE_UUID)
     {
         parent::__construct($dm);
         $this->document = $document;
diff --git a/lib/Doctrine/ODM/PHPCR/ReferrersCollection.php b/lib/Doctrine/ODM/PHPCR/ReferrersCollection.php
index 9cde025a7..443b4e572 100644
--- a/lib/Doctrine/ODM/PHPCR/ReferrersCollection.php
+++ b/lib/Doctrine/ODM/PHPCR/ReferrersCollection.php
@@ -32,7 +32,7 @@ class ReferrersCollection extends PersistentCollection
      * @param string|null              $locale   the locale to use
      * @param string|null              $refClass class the referrer document must be instanceof
      */
-    public function __construct(DocumentManagerInterface $dm, object $document, string $type = null, string $name = null, string $locale = null, string $refClass = null)
+    public function __construct(DocumentManagerInterface $dm, object $document, ?string $type = null, ?string $name = null, ?string $locale = null, ?string $refClass = null)
     {
         parent::__construct($dm);
         $this->document = $document;
@@ -51,7 +51,7 @@ public function __construct(DocumentManagerInterface $dm, object $document, stri
      * @param string|null              $refClass       class the referrer document must be instanceof
      * @param bool                     $forceOverwrite If to force the database to be forced to the state of the collection
      */
-    public static function createFromCollection(DocumentManagerInterface $dm, object $document, $collection, string $type = null, string $name = null, string $refClass = null, bool $forceOverwrite = false): self
+    public static function createFromCollection(DocumentManagerInterface $dm, object $document, $collection, ?string $type = null, ?string $name = null, ?string $refClass = null, bool $forceOverwrite = false): self
     {
         $referrerCollection = new self($dm, $document, $type, $name, null, $refClass);
         $referrerCollection->initializeFromCollection($collection, $forceOverwrite);
diff --git a/lib/Doctrine/ODM/PHPCR/Tools/Console/Command/DocumentConvertTranslationCommand.php b/lib/Doctrine/ODM/PHPCR/Tools/Console/Command/DocumentConvertTranslationCommand.php
index 80d783d41..b716f7786 100644
--- a/lib/Doctrine/ODM/PHPCR/Tools/Console/Command/DocumentConvertTranslationCommand.php
+++ b/lib/Doctrine/ODM/PHPCR/Tools/Console/Command/DocumentConvertTranslationCommand.php
@@ -24,7 +24,7 @@ class DocumentConvertTranslationCommand extends Command
 {
     private ?TranslationConverter $translationConverter;
 
-    public function __construct($name = null, TranslationConverter $translationConverter = null)
+    public function __construct($name = null, ?TranslationConverter $translationConverter = null)
     {
         parent::__construct($name);
         $this->translationConverter = $translationConverter;
diff --git a/lib/Doctrine/ODM/PHPCR/Tools/Console/Helper/DocumentManagerHelper.php b/lib/Doctrine/ODM/PHPCR/Tools/Console/Helper/DocumentManagerHelper.php
index f193117e0..bb1c45efa 100644
--- a/lib/Doctrine/ODM/PHPCR/Tools/Console/Helper/DocumentManagerHelper.php
+++ b/lib/Doctrine/ODM/PHPCR/Tools/Console/Helper/DocumentManagerHelper.php
@@ -13,7 +13,7 @@ final class DocumentManagerHelper extends PhpcrHelper
 {
     private ?DocumentManagerInterface $dm;
 
-    public function __construct(SessionInterface $session = null, DocumentManagerInterface $dm = null)
+    public function __construct(?SessionInterface $session = null, ?DocumentManagerInterface $dm = null)
     {
         if (!$session && $dm) {
             $session = $dm->getPhpcrSession();
diff --git a/lib/Doctrine/ODM/PHPCR/Tools/Helper/PrefetchHelper.php b/lib/Doctrine/ODM/PHPCR/Tools/Helper/PrefetchHelper.php
index 0acee973f..7fe750826 100644
--- a/lib/Doctrine/ODM/PHPCR/Tools/Helper/PrefetchHelper.php
+++ b/lib/Doctrine/ODM/PHPCR/Tools/Helper/PrefetchHelper.php
@@ -23,7 +23,7 @@ class PrefetchHelper
     /**
      * @param NodeInterface[] $nodes
      */
-    public function prefetch(DocumentManagerInterface $dm, iterable $nodes, string $locale = null): void
+    public function prefetch(DocumentManagerInterface $dm, iterable $nodes, ?string $locale = null): void
     {
         if (0 === count($nodes)) {
             return;
@@ -68,7 +68,7 @@ public function prefetchReferences(ClassMetadata $class, NodeInterface $node): v
      *
      * @param NodeInterface $node the node to prefetch parent and children for
      */
-    public function prefetchHierarchy(ClassMetadata $class, NodeInterface $node, string $locale = null): void
+    public function prefetchHierarchy(ClassMetadata $class, NodeInterface $node, ?string $locale = null): void
     {
         $prefetch = $this->collectPrefetchHierarchy($class, $node, $locale);
         if (count($prefetch)) {
@@ -112,7 +112,7 @@ public function collectPrefetchReferences(ClassMetadata $class, NodeInterface $n
      *
      * @return string[] list of absolute paths to nodes that should be prefetched
      */
-    public function collectPrefetchHierarchy(ClassMetadata $class, NodeInterface $node, string $locale = null): array
+    public function collectPrefetchHierarchy(ClassMetadata $class, NodeInterface $node, ?string $locale = null): array
     {
         $prefetch = [];
         if ($class->parentMapping && $node->getDepth() > 0) {
diff --git a/lib/Doctrine/ODM/PHPCR/Tools/Test/QueryBuilderTester.php b/lib/Doctrine/ODM/PHPCR/Tools/Test/QueryBuilderTester.php
index af6b4e46c..637817fae 100644
--- a/lib/Doctrine/ODM/PHPCR/Tools/Test/QueryBuilderTester.php
+++ b/lib/Doctrine/ODM/PHPCR/Tools/Test/QueryBuilderTester.php
@@ -83,7 +83,7 @@ public function getNode(string $path): AbstractNode
      * Note that paths here do not include indexes. They need to be
      * inferred mentally.
      */
-    public function dumpPaths(AbstractNode $node = null): string
+    public function dumpPaths(?AbstractNode $node = null): string
     {
         $children = [];
         $paths = [];
@@ -127,7 +127,7 @@ public function getPath(AbstractNode $node): string
      *
      * @return AbstractNode[]
      */
-    public function getAllNodes(AbstractNode $node = null): array
+    public function getAllNodes(?AbstractNode $node = null): array
     {
         $nodes = [];
         if (!$node) {
diff --git a/lib/Doctrine/ODM/PHPCR/Translation/LocaleChooser/LocaleChooser.php b/lib/Doctrine/ODM/PHPCR/Translation/LocaleChooser/LocaleChooser.php
index 24dc11ea9..dee7e12b7 100644
--- a/lib/Doctrine/ODM/PHPCR/Translation/LocaleChooser/LocaleChooser.php
+++ b/lib/Doctrine/ODM/PHPCR/Translation/LocaleChooser/LocaleChooser.php
@@ -84,7 +84,7 @@ public function setFallbackLocales(string $locale, array $order, bool $replace):
         $this->localePreference[$locale] = $order;
     }
 
-    public function getFallbackLocales(?object $document, ClassMetadata $metadata, string $forLocale = null): array
+    public function getFallbackLocales(?object $document, ClassMetadata $metadata, ?string $forLocale = null): array
     {
         if (is_null($forLocale)) {
             return $this->localePreference[$this->getLocale()];
diff --git a/lib/Doctrine/ODM/PHPCR/Translation/LocaleChooser/LocaleChooserInterface.php b/lib/Doctrine/ODM/PHPCR/Translation/LocaleChooser/LocaleChooserInterface.php
index 44744ee1f..c977ddc0e 100644
--- a/lib/Doctrine/ODM/PHPCR/Translation/LocaleChooser/LocaleChooserInterface.php
+++ b/lib/Doctrine/ODM/PHPCR/Translation/LocaleChooser/LocaleChooserInterface.php
@@ -64,7 +64,7 @@ public function setFallbackLocales(string $locale, array $order, bool $replace):
      *
      * @throws MissingTranslationException
      */
-    public function getFallbackLocales(?object $document, ClassMetadata $metadata, string $forLocale = null): array;
+    public function getFallbackLocales(?object $document, ClassMetadata $metadata, ?string $forLocale = null): array;
 
     /**
      * Get the locale of the current session.
diff --git a/lib/Doctrine/ODM/PHPCR/Translation/TranslationStrategy/AttributeTranslationStrategy.php b/lib/Doctrine/ODM/PHPCR/Translation/TranslationStrategy/AttributeTranslationStrategy.php
index a4155ea3d..dbba0565a 100644
--- a/lib/Doctrine/ODM/PHPCR/Translation/TranslationStrategy/AttributeTranslationStrategy.php
+++ b/lib/Doctrine/ODM/PHPCR/Translation/TranslationStrategy/AttributeTranslationStrategy.php
@@ -174,7 +174,7 @@ public function getTranslatedPropertyPath(string $alias, string $propertyName, s
     public function alterQueryForTranslation(
         QueryObjectModelFactoryInterface $qomf,
         SourceInterface &$selector,
-        ConstraintInterface &$constraint = null,
+        ?ConstraintInterface &$constraint,
         string $alias,
         string $locale
     ): void {
diff --git a/lib/Doctrine/ODM/PHPCR/Translation/TranslationStrategy/ChildTranslationStrategy.php b/lib/Doctrine/ODM/PHPCR/Translation/TranslationStrategy/ChildTranslationStrategy.php
index 63bfe789a..e5346e612 100644
--- a/lib/Doctrine/ODM/PHPCR/Translation/TranslationStrategy/ChildTranslationStrategy.php
+++ b/lib/Doctrine/ODM/PHPCR/Translation/TranslationStrategy/ChildTranslationStrategy.php
@@ -128,7 +128,7 @@ public function getTranslatedPropertyPath(string $alias, string $propertyName, s
     public function alterQueryForTranslation(
         QueryObjectModelFactoryInterface $qomf,
         SourceInterface &$selector,
-        ConstraintInterface &$constraint = null,
+        ?ConstraintInterface &$constraint,
         string $alias,
         string $locale
     ): void {
diff --git a/lib/Doctrine/ODM/PHPCR/Translation/TranslationStrategy/NonTranslatedStrategy.php b/lib/Doctrine/ODM/PHPCR/Translation/TranslationStrategy/NonTranslatedStrategy.php
index 6301fc4a6..2762fb4b9 100644
--- a/lib/Doctrine/ODM/PHPCR/Translation/TranslationStrategy/NonTranslatedStrategy.php
+++ b/lib/Doctrine/ODM/PHPCR/Translation/TranslationStrategy/NonTranslatedStrategy.php
@@ -88,7 +88,7 @@ public function getTranslatedPropertyPath(string $alias, string $propertyName, s
     public function alterQueryForTranslation(
         QueryObjectModelFactoryInterface $qomf,
         SourceInterface &$selector,
-        ConstraintInterface &$constraint = null,
+        ?ConstraintInterface &$constraint,
         string $alias,
         string $locale
     ): void {
diff --git a/lib/Doctrine/ODM/PHPCR/Translation/TranslationStrategy/TranslationStrategyInterface.php b/lib/Doctrine/ODM/PHPCR/Translation/TranslationStrategy/TranslationStrategyInterface.php
index c3c4978d7..e2493984f 100644
--- a/lib/Doctrine/ODM/PHPCR/Translation/TranslationStrategy/TranslationStrategyInterface.php
+++ b/lib/Doctrine/ODM/PHPCR/Translation/TranslationStrategy/TranslationStrategyInterface.php
@@ -107,7 +107,7 @@ public function getTranslatedPropertyPath(string $alias, string $propertyName, s
     public function alterQueryForTranslation(
         QueryObjectModelFactoryInterface $qomf,
         SourceInterface &$selector,
-        ConstraintInterface &$constraint = null,
+        ?ConstraintInterface &$constraint,
         string $alias,
         string $locale
     ): void;
diff --git a/lib/Doctrine/ODM/PHPCR/UnitOfWork.php b/lib/Doctrine/ODM/PHPCR/UnitOfWork.php
index 6a8571323..0509b5ba1 100644
--- a/lib/Doctrine/ODM/PHPCR/UnitOfWork.php
+++ b/lib/Doctrine/ODM/PHPCR/UnitOfWork.php
@@ -273,7 +273,7 @@ public function getOrCreateDocument(?string $className, NodeInterface $node, arr
      *
      * @param \Iterator|array $nodes
      *
-     * @throws Exception\InvalidArgumentException
+     * @throws InvalidArgumentException
      * @throws PHPCRException
      */
     public function getOrCreateDocuments(?string $className, iterable $nodes, array $hints = []): array
@@ -553,7 +553,7 @@ public function getOrCreateDocuments(?string $className, iterable $nodes, array
     /**
      * Get the existing document or proxy or create a new one for this PHPCR Node.
      */
-    public function getOrCreateProxyFromNode(NodeInterface $node, string $locale = null): object
+    public function getOrCreateProxyFromNode(NodeInterface $node, ?string $locale = null): object
     {
         $targetId = $node->getPath();
         $className = $this->documentClassMapper->getClassName($this->dm, $node);
@@ -565,7 +565,7 @@ public function getOrCreateProxyFromNode(NodeInterface $node, string $locale = n
      * Get the existing document or proxy for this id of this class, or create
      * a new one.
      */
-    public function getOrCreateProxy(string $targetId, string $className, string $locale = null): object
+    public function getOrCreateProxy(string $targetId, string $className, ?string $locale = null): object
     {
         $document = $this->getDocumentById($targetId);
 
@@ -1085,7 +1085,7 @@ private function getChildNodename(string $parentId, string $nodename, object $ch
     }
 
     /**
-     * @throws Exception\InvalidArgumentException
+     * @throws InvalidArgumentException
      * @throws PHPCRException
      */
     private function computeAssociationChanges(object $document, ClassMetadata $class, string $oid, bool $isNew, array $changeSet, string $assocType): void
@@ -1514,7 +1514,7 @@ public function computeChangeSet(ClassMetadata $class, object $document): void
      *
      * @return object the child instance (if we are replacing a child this can be a different instance than was originally provided)
      */
-    private function computeChildChanges(array $mapping, object $child, string $parentId, string $nodename, object $parent = null): object
+    private function computeChildChanges(array $mapping, object $child, string $parentId, string $nodename, ?object $parent = null): object
     {
         $targetClass = $this->dm->getClassMetadata(get_class($child));
         $state = $this->getDocumentState($child);
@@ -1608,7 +1608,7 @@ private function computeReferrerChanges(array $mapping, object $referrer): void
      *
      * @param int|null $overrideIdGenerator type of the id generator if not the default
      */
-    public function persistNew(ClassMetadata $class, object $document, int $overrideIdGenerator = null, object $parent = null): void
+    public function persistNew(ClassMetadata $class, object $document, ?int $overrideIdGenerator = null, ?object $parent = null): void
     {
         if ($invoke = $this->eventListenersInvoker->getSubscribedSystems($class, Event::prePersist)) {
             $this->eventListenersInvoker->invoke(
@@ -1710,7 +1710,7 @@ private function cascadeMergeCollection(Collection $managedCol, array $mapping):
     /**
      * @param array|null $assoc Information for association when necessary
      */
-    private function doMerge(object $document, array &$visited, object $prevManagedCopy = null, array $assoc = null): object
+    private function doMerge(object $document, array &$visited, ?object $prevManagedCopy = null, ?array $assoc = null): object
     {
         $oid = \spl_object_hash($document);
         if (array_key_exists($oid, $visited)) {
@@ -2945,7 +2945,7 @@ public function getDocumentId($document, bool $throw = true): ?string
      * Try to determine the document id first by looking into the document,
      * but if not mapped, look into the document id cache.
      */
-    public function determineDocumentId(object $document, ClassMetadata $metadata = null): ?string
+    public function determineDocumentId(object $document, ?ClassMetadata $metadata = null): ?string
     {
         if (!$metadata) {
             $metadata = $this->dm->getClassMetadata(get_class($document));
@@ -3182,7 +3182,7 @@ protected function doLoadDatabaseTranslation(object $document, ClassMetadata $me
      * If the document is not translatable, this method returns immediately
      * and without error.
      */
-    public function doLoadTranslation(object $document, ClassMetadata $metadata, string $locale = null, bool $fallback = false, bool $refresh = false): void
+    public function doLoadTranslation(object $document, ClassMetadata $metadata, ?string $locale = null, bool $fallback = false, bool $refresh = false): void
     {
         if (!$this->isDocumentTranslatable($metadata)) {
             return;
@@ -3398,7 +3398,7 @@ private function setLocale(object $document, ClassMetadata $metadata, ?string $l
      *
      * @return string|null the current locale of $document or null if it is not translatable
      */
-    public function getCurrentLocale(object $document, ClassMetadata $metadata = null): ?string
+    public function getCurrentLocale(object $document, ?ClassMetadata $metadata = null): ?string
     {
         if (null === $metadata) {
             $metadata = $this->dm->getClassMetadata(get_class($document));
@@ -3434,7 +3434,7 @@ public function isDocumentTranslatable(ClassMetadata $metadata): bool
             && 0 !== count($metadata->translatableFields);
     }
 
-    private static function objToStr(object $obj, DocumentManagerInterface $dm = null)
+    private static function objToStr(object $obj, ?DocumentManagerInterface $dm = null)
     {
         $string = method_exists($obj, '__toString')
             ? (string) $obj
@@ -3547,7 +3547,7 @@ private function getReferenceManyCollectionTypeFromMetadata(array $referenceFiel
      *
      * @return int previous fetch depth value
      */
-    public function setFetchDepth(int $fetchDepth = null): int
+    public function setFetchDepth(?int $fetchDepth = null): int
     {
         if (!$this->useFetchDepth
             || !method_exists($this->session, 'getSessionOption')
diff --git a/tests/Doctrine/Tests/Models/CMS/CmsAddress.php b/tests/Doctrine/Tests/Models/CMS/CmsAddress.php
index 6fb458139..330fd014e 100644
--- a/tests/Doctrine/Tests/Models/CMS/CmsAddress.php
+++ b/tests/Doctrine/Tests/Models/CMS/CmsAddress.php
@@ -65,7 +65,7 @@ public function setUser(CmsUser $user)
 
 class CmsAddressRepository extends DocumentRepository implements RepositoryIdInterface
 {
-    public function generateId(object $document, object $parent = null): string
+    public function generateId(object $document, ?object $parent = null): string
     {
         return '/functional/'.$document->city.'_'.$document->zip;
     }
diff --git a/tests/Doctrine/Tests/Models/CMS/CmsArticlePerson.php b/tests/Doctrine/Tests/Models/CMS/CmsArticlePerson.php
index 2e096bb3c..883e07715 100644
--- a/tests/Doctrine/Tests/Models/CMS/CmsArticlePerson.php
+++ b/tests/Doctrine/Tests/Models/CMS/CmsArticlePerson.php
@@ -57,7 +57,7 @@ public function getName()
 
 class CmsArticlePersonRepository extends DocumentRepository implements RepositoryIdInterface
 {
-    public function generateId(object $document, object $parent = null): string
+    public function generateId(object $document, ?object $parent = null): string
     {
         return '/functional/'.$document->name;
     }
diff --git a/tests/Doctrine/Tests/Models/CMS/CmsItem.php b/tests/Doctrine/Tests/Models/CMS/CmsItem.php
index 04331fa66..c1deffe22 100644
--- a/tests/Doctrine/Tests/Models/CMS/CmsItem.php
+++ b/tests/Doctrine/Tests/Models/CMS/CmsItem.php
@@ -53,7 +53,7 @@ public function getName()
 
 class CmsItemRepository extends DocumentRepository implements RepositoryIdInterface
 {
-    public function generateId(object $document, object $parent = null): string
+    public function generateId(object $document, ?object $parent = null): string
     {
         return '/functional/'.$document->name;
     }
diff --git a/tests/Doctrine/Tests/Models/CMS/CmsPage.php b/tests/Doctrine/Tests/Models/CMS/CmsPage.php
index 4ff24f1c0..c6dc3e492 100644
--- a/tests/Doctrine/Tests/Models/CMS/CmsPage.php
+++ b/tests/Doctrine/Tests/Models/CMS/CmsPage.php
@@ -82,7 +82,7 @@ public function removeItem($item)
 
 class CmsPageRepository extends DocumentRepository implements RepositoryIdInterface
 {
-    public function generateId(object $document, object $parent = null): string
+    public function generateId(object $document, ?object $parent = null): string
     {
         return '/functional/'.$document->title;
     }
diff --git a/tests/Doctrine/Tests/Models/CMS/CmsPageTranslatable.php b/tests/Doctrine/Tests/Models/CMS/CmsPageTranslatable.php
index 537292a91..868a0bf0c 100644
--- a/tests/Doctrine/Tests/Models/CMS/CmsPageTranslatable.php
+++ b/tests/Doctrine/Tests/Models/CMS/CmsPageTranslatable.php
@@ -95,7 +95,7 @@ public function getLocale()
 
 class CmsPageTranslatableRepository extends DocumentRepository implements RepositoryIdInterface
 {
-    public function generateId(object $document, object $parent = null): string
+    public function generateId(object $document, ?object $parent = null): string
     {
         return '/functional/'.$document->title;
     }
diff --git a/tests/Doctrine/Tests/Models/CMS/CmsProfile.php b/tests/Doctrine/Tests/Models/CMS/CmsProfile.php
index 348b4269c..45f05f13d 100644
--- a/tests/Doctrine/Tests/Models/CMS/CmsProfile.php
+++ b/tests/Doctrine/Tests/Models/CMS/CmsProfile.php
@@ -54,7 +54,7 @@ public function getUser()
 
 class CmsProfileRepository extends DocumentRepository implements RepositoryIdInterface
 {
-    public function generateId(object $document, object $parent = null): string
+    public function generateId(object $document, ?object $parent = null): string
     {
         return '/functional/'.$document->user->username.'/'.$document->data;
     }
diff --git a/tests/Doctrine/Tests/Models/CMS/CmsTeamUser.php b/tests/Doctrine/Tests/Models/CMS/CmsTeamUser.php
index 33470242b..b1c0bf361 100644
--- a/tests/Doctrine/Tests/Models/CMS/CmsTeamUser.php
+++ b/tests/Doctrine/Tests/Models/CMS/CmsTeamUser.php
@@ -23,7 +23,7 @@ public function setParentDocument($parent)
 
 class CmsTeamUserRepository extends DocumentRepository implements RepositoryIdInterface
 {
-    public function generateId(object $document, object $parent = null): string
+    public function generateId(object $document, ?object $parent = null): string
     {
         return $document->parent->id.'/'.$document->username;
     }
diff --git a/tests/Doctrine/Tests/Models/CMS/CmsUser.php b/tests/Doctrine/Tests/Models/CMS/CmsUser.php
index 15ece8cb7..7d801a25b 100644
--- a/tests/Doctrine/Tests/Models/CMS/CmsUser.php
+++ b/tests/Doctrine/Tests/Models/CMS/CmsUser.php
@@ -108,7 +108,7 @@ public function getProfiles()
 
 class CmsUserRepository extends DocumentRepository implements RepositoryIdInterface
 {
-    public function generateId(object $document, object $parent = null): string
+    public function generateId(object $document, ?object $parent = null): string
     {
         return '/functional/'.$document->username;
     }
diff --git a/tests/Doctrine/Tests/Models/CMS/CmsUserTranslatable.php b/tests/Doctrine/Tests/Models/CMS/CmsUserTranslatable.php
index ef331c26c..9db1bc0a3 100644
--- a/tests/Doctrine/Tests/Models/CMS/CmsUserTranslatable.php
+++ b/tests/Doctrine/Tests/Models/CMS/CmsUserTranslatable.php
@@ -96,7 +96,7 @@ public function getGroups()
 
 class CmsUserTranslatableRepository extends DocumentRepository implements RepositoryIdInterface
 {
-    public function generateId(object $document, object $parent = null): string
+    public function generateId(object $document, ?object $parent = null): string
     {
         return '/functional/'.$document->username;
     }
diff --git a/tests/Doctrine/Tests/ODM/PHPCR/DocumentClassMapperTest.php b/tests/Doctrine/Tests/ODM/PHPCR/DocumentClassMapperTest.php
index 4fb9d62c2..13c99475c 100644
--- a/tests/Doctrine/Tests/ODM/PHPCR/DocumentClassMapperTest.php
+++ b/tests/Doctrine/Tests/ODM/PHPCR/DocumentClassMapperTest.php
@@ -14,7 +14,7 @@
 use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
 
-class DocumentClassMapperTest extends Testcase
+class DocumentClassMapperTest extends TestCase
 {
     private const CLASS_GENERIC = Generic::class;
     private const CLASS_TEST_1 = 'Test\Class1';
diff --git a/tests/Doctrine/Tests/ODM/PHPCR/Functional/BasicCrudTest.php b/tests/Doctrine/Tests/ODM/PHPCR/Functional/BasicCrudTest.php
index b8c786946..738a1d49a 100644
--- a/tests/Doctrine/Tests/ODM/PHPCR/Functional/BasicCrudTest.php
+++ b/tests/Doctrine/Tests/ODM/PHPCR/Functional/BasicCrudTest.php
@@ -169,7 +169,7 @@ public function testGetUuuidAfterPersist(): void
 
     public function testExistingUuuid(): void
     {
-        $testUuid = UuidHelper::generateUUID();
+        $testUuid = UUIDHelper::generateUUID();
 
         $newUser = new UserWithUuid();
         $newUser->username = 'test';
@@ -722,7 +722,7 @@ class User6 extends User5
 
 class User3Repository extends DocumentRepository implements RepositoryIdInterface
 {
-    public function generateId(object $document, object $parent = null): string
+    public function generateId(object $document, ?object $parent = null): string
     {
         return '/functional/'.$document->username;
     }
diff --git a/tests/Doctrine/Tests/ODM/PHPCR/Functional/Hierarchy/ChildrenTest.php b/tests/Doctrine/Tests/ODM/PHPCR/Functional/Hierarchy/ChildrenTest.php
index cc129e38b..12ede9a21 100644
--- a/tests/Doctrine/Tests/ODM/PHPCR/Functional/Hierarchy/ChildrenTest.php
+++ b/tests/Doctrine/Tests/ODM/PHPCR/Functional/Hierarchy/ChildrenTest.php
@@ -727,7 +727,7 @@ public function __construct()
 
 class ChildrenTestObjRepository extends DocumentRepository implements RepositoryIdInterface
 {
-    public function generateId(object $document, object $parent = null): string
+    public function generateId(object $document, ?object $parent = null): string
     {
         if ($document->id) {
             return $document->id;
diff --git a/tests/Doctrine/Tests/ODM/PHPCR/Functional/Mapping/AttributeMappingTest.php b/tests/Doctrine/Tests/ODM/PHPCR/Functional/Mapping/AttributeMappingTest.php
index d6e422012..2a91ea4de 100644
--- a/tests/Doctrine/Tests/ODM/PHPCR/Functional/Mapping/AttributeMappingTest.php
+++ b/tests/Doctrine/Tests/ODM/PHPCR/Functional/Mapping/AttributeMappingTest.php
@@ -309,7 +309,7 @@ class RepositoryIdStrategy
 }
 class Repository extends DocumentRepository implements RepositoryIdInterface
 {
-    public function generateId(object $document, object $parent = null): string
+    public function generateId(object $document, ?object $parent = null): string
     {
         return '/functional/'.str_replace(' ', '-', $document->title);
     }
diff --git a/tests/Doctrine/Tests/ODM/PHPCR/Mapping/Model/DocumentRepository.php b/tests/Doctrine/Tests/ODM/PHPCR/Mapping/Model/DocumentRepository.php
index 392bd2dd6..05789a977 100644
--- a/tests/Doctrine/Tests/ODM/PHPCR/Mapping/Model/DocumentRepository.php
+++ b/tests/Doctrine/Tests/ODM/PHPCR/Mapping/Model/DocumentRepository.php
@@ -10,7 +10,7 @@
  */
 class DocumentRepository extends BaseDocumentRepository implements RepositoryIdInterface
 {
-    public function generateId(object $document, object $parent = null): string
+    public function generateId(object $document, ?object $parent = null): string
     {
         return '/functional/'.rand();
     }
diff --git a/tests/Doctrine/Tests/ODM/PHPCR/PHPCRFunctionalTestCase.php b/tests/Doctrine/Tests/ODM/PHPCR/PHPCRFunctionalTestCase.php
index fd511af10..9da2c2101 100644
--- a/tests/Doctrine/Tests/ODM/PHPCR/PHPCRFunctionalTestCase.php
+++ b/tests/Doctrine/Tests/ODM/PHPCR/PHPCRFunctionalTestCase.php
@@ -21,7 +21,7 @@ abstract class PHPCRFunctionalTestCase extends TestCase
      */
     private $sessions = [];
 
-    public function createDocumentManager(array $paths = null): DocumentManager
+    public function createDocumentManager(?array $paths = null): DocumentManager
     {
         if (empty($paths)) {
             $paths = [__DIR__.'/../../Models'];
diff --git a/tests/Doctrine/Tests/ODM/PHPCR/Query/QueryTest.php b/tests/Doctrine/Tests/ODM/PHPCR/Query/QueryTest.php
index 7863bc64d..d3a3c5642 100644
--- a/tests/Doctrine/Tests/ODM/PHPCR/Query/QueryTest.php
+++ b/tests/Doctrine/Tests/ODM/PHPCR/Query/QueryTest.php
@@ -14,7 +14,7 @@
 /**
  * @group unit
  */
-class QueryTest extends Testcase
+class QueryTest extends TestCase
 {
     /**
      * @var QueryInterface&MockObject
@@ -120,9 +120,15 @@ public function testExecuteParameters(): void
     {
         $this->phpcrQuery
             ->method('bindValue')
-            ->withConsecutive(['foo', 'bar'], ['bar', 'foo'])
+            ->with(
+                $this->callback(function (string $key): bool {
+                    return 'kfoo' === $key || 'kbar' === $key;
+                }), $this->callback(function (string $value): bool {
+                    return 'bar' === $value || 'foo' === $value;
+                })
+            )
         ;
-        $this->query->execute(['foo' => 'bar', 'bar' => 'foo']);
+        $this->query->execute(['kfoo' => 'bar', 'kbar' => 'foo']);
     }
 
     public function testExecuteMaxResults(): void
diff --git a/tests/phpunit_doctrine_dbal.xml.dist b/tests/phpunit_doctrine_dbal.xml.dist
index 19bc21242..ec0ce1873 100644
--- a/tests/phpunit_doctrine_dbal.xml.dist
+++ b/tests/phpunit_doctrine_dbal.xml.dist
@@ -10,6 +10,7 @@
         <var name="jackalope.doctrine.dbal.user" value="root" />
         <var name="jackalope.doctrine.dbal.password" value="" />
         <var name="jackalope.doctrine.dbal.dbname" value="phpcr_odm_tests" />
+        <var name="jackalope.doctrine.dbal.charset" value="utf8mb4" />
         <var name="DOCTRINE_PHPCR_USER" value="admin" />
         <var name="DOCTRINE_PHPCR_PASS" value="admin" />
         <var name="DOCTRINE_PHPCR_WORKSPACE" value="default" />