diff --git a/composer.json b/composer.json
index cfee54dcc..913a9b2f9 100644
--- a/composer.json
+++ b/composer.json
@@ -23,7 +23,7 @@
         "doctrine/collections": "^2.0",
         "doctrine/common": "^2.4 || ^3.0",
         "doctrine/event-manager": "^1.0 || ^2.0",
-        "doctrine/persistence": "^3.0",
+        "doctrine/persistence": "^3.0 || ^4.0",
         "phpcr/phpcr": "^2.1.1",
         "phpcr/phpcr-implementation": "^2.1",
         "phpcr/phpcr-utils": "^1.3.0 || ^2.0",
diff --git a/lib/Doctrine/ODM/PHPCR/Decorator/DocumentManagerDecorator.php b/lib/Doctrine/ODM/PHPCR/Decorator/DocumentManagerDecorator.php
index ace7e8628..2f4aa24a8 100644
--- a/lib/Doctrine/ODM/PHPCR/Decorator/DocumentManagerDecorator.php
+++ b/lib/Doctrine/ODM/PHPCR/Decorator/DocumentManagerDecorator.php
@@ -2,7 +2,6 @@
 
 namespace Doctrine\ODM\PHPCR\Decorator;
 
-use Doctrine\Common\Collections\Collection;
 use Doctrine\Common\EventManager;
 use Doctrine\ODM\PHPCR\ChildrenCollection;
 use Doctrine\ODM\PHPCR\Configuration;
@@ -15,6 +14,7 @@
 use Doctrine\ODM\PHPCR\Translation\LocaleChooser\LocaleChooserInterface;
 use Doctrine\ODM\PHPCR\Translation\TranslationStrategy\TranslationStrategyInterface;
 use Doctrine\ODM\PHPCR\UnitOfWork;
+use Doctrine\Persistence\ObjectManager;
 use Doctrine\Persistence\ObjectManagerDecorator;
 use PHPCR\NodeInterface;
 use PHPCR\PropertyType;
@@ -26,13 +26,15 @@
  * Base class for DocumentManager decorators.
  *
  * @since 1.3
+ *
+ * @extends ObjectManagerDecorator<DocumentManagerInterface>
  */
 abstract class DocumentManagerDecorator extends ObjectManagerDecorator implements DocumentManagerInterface
 {
     /**
      * @var DocumentManagerInterface
      */
-    protected $wrapped;
+    protected ObjectManager $wrapped;
 
     public function __construct(DocumentManagerInterface $wrapped)
     {
@@ -100,7 +102,7 @@ public function find(?string $className, $id): ?object
         return $this->wrapped->find($className, $id);
     }
 
-    public function findMany(?string $className, array $ids): Collection
+    public function findMany(?string $className, array $ids): array
     {
         return $this->wrapped->findMany($className, $ids);
     }
@@ -140,7 +142,7 @@ 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): array
     {
         return $this->wrapped->getDocumentsByPhpcrQuery($query, $className, $primarySelector);
     }
diff --git a/lib/Doctrine/ODM/PHPCR/DocumentManager.php b/lib/Doctrine/ODM/PHPCR/DocumentManager.php
index 215b0ba59..f892b133d 100644
--- a/lib/Doctrine/ODM/PHPCR/DocumentManager.php
+++ b/lib/Doctrine/ODM/PHPCR/DocumentManager.php
@@ -211,7 +211,7 @@ public function find(?string $className, $id): ?object
         }
     }
 
-    public function findMany(?string $className, array $ids): Collection
+    public function findMany(?string $className, array $ids): array
     {
         // when loading duplicate ID's the resulting response would be a collection of unique ids,
         // but having duplicates would also cause a lot of overhead as well as break translation loading,
@@ -343,7 +343,7 @@ public function createPhpcrQueryBuilder(): PhpcrQueryBuilder
         return new PhpcrQueryBuilder($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): array
     {
         $this->errorIfClosed();
 
@@ -372,11 +372,9 @@ public function getDocumentsByPhpcrQuery(QueryInterface $query, ?string $classNa
      *      for the default language and that is used to store. The field is
      *      updated with the locale.
      *
-     * @param object $document the document to persist
-     *
      * @throws InvalidArgumentException if $document is not an object
      */
-    public function persist($document): void
+    public function persist(object $document): void
     {
         if (!is_object($document)) {
             throw new InvalidArgumentException('Parameter $document needs to be an object, '.gettype($document).' given');
@@ -447,17 +445,9 @@ public function reorder(object $document, string $srcName, string $targetName, b
      * Be aware of the PHPCR tree structure: this removes all nodes with a path under
      * the path of this object, even if there are no Parent / Child mappings
      * that make the relationship explicit.
-     *
-     * @param object $document
-     *
-     * @throws InvalidArgumentException if $document is not an object
      */
-    public function remove($document): void
+    public function remove(object $document): void
     {
-        if (!is_object($document)) {
-            throw new InvalidArgumentException('Parameter $document needs to be an object, '.gettype($document).' given');
-        }
-
         $this->errorIfClosed();
         $this->unitOfWork->scheduleRemove($document);
     }
@@ -471,17 +461,9 @@ public function remove($document): void
      * removal of the object) will not be synchronized to the database.
      * Objects which previously referenced the detached object will continue to
      * reference it.
-     *
-     * @param object $document the object to detach
-     *
-     * @throws InvalidArgumentException if $document is not an object
      */
-    public function detach($document): void
+    public function detach(object $document): void
     {
-        if (!is_object($document)) {
-            throw new InvalidArgumentException('Parameter $document needs to be an object, '.gettype($document).' given');
-        }
-
         $this->errorIfClosed();
         $this->unitOfWork->detach($document);
     }
@@ -490,17 +472,9 @@ public function detach($document): void
      * {@inheritdoc}
      *
      * Refresh the given document by querying the PHPCR to get the current state.
-     *
-     * @param object $document
-     *
-     * @throws InvalidArgumentException if $document is not an object
      */
-    public function refresh($document): void
+    public function refresh(object $document): void
     {
-        if (!is_object($document)) {
-            throw new InvalidArgumentException('Parameter $document needs to be an object, '.gettype($document).' given');
-        }
-
         $this->errorIfClosed();
         $this->unitOfWork->refresh($document);
     }
@@ -594,19 +568,9 @@ public function findVersionByName(?string $className, string $id, string $versio
      * {@inheritdoc}
      *
      * Check if this repository contains the object
-     *
-     * @param object $document
-     *
-     * @return bool true if the repository contains the object, false otherwise
-     *
-     * @throws InvalidArgumentException if $document is not an object
      */
-    public function contains($document): bool
+    public function contains(object $document): bool
     {
-        if (!is_object($document)) {
-            throw new InvalidArgumentException('Parameter $document needs to be an object, '.gettype($document).' given');
-        }
-
         return $this->unitOfWork->contains($document);
     }
 
@@ -637,12 +601,8 @@ public function close(): void
         $this->closed = true;
     }
 
-    public function initializeObject($document): void
+    public function initializeObject(object $document): void
     {
-        if (!is_object($document)) {
-            throw new InvalidArgumentException('Parameter $document needs to be an object, '.gettype($document).' given');
-        }
-
         $this->unitOfWork->initializeObject($document);
     }
 
diff --git a/lib/Doctrine/ODM/PHPCR/DocumentManagerInterface.php b/lib/Doctrine/ODM/PHPCR/DocumentManagerInterface.php
index b158a6761..25449b4a6 100644
--- a/lib/Doctrine/ODM/PHPCR/DocumentManagerInterface.php
+++ b/lib/Doctrine/ODM/PHPCR/DocumentManagerInterface.php
@@ -20,7 +20,6 @@
 
 namespace Doctrine\ODM\PHPCR;
 
-use Doctrine\Common\Collections\Collection;
 use Doctrine\Common\EventManager;
 use Doctrine\ODM\PHPCR\Exception\InvalidArgumentException;
 use Doctrine\ODM\PHPCR\Mapping\ClassMetadata as PhpcrClassMetadata;
@@ -125,7 +124,13 @@ public function isOpen(): bool;
      * @param string|null $className optional object class name to use
      * @param string      $id        the path or uuid of the document to find
      *
+     * @phpstan-param class-string<T>|null $className
+     *
      * @return object|null the document if found, otherwise null
+     *
+     * @phpstan-return T|null
+     *
+     * @template T of object
      */
     public function find(?string $className, $id): ?object;
 
@@ -137,10 +142,16 @@ public function find(?string $className, $id): ?object;
      * @param string[]    $ids       List of repository paths and/or uuids to
      *                               find documents. Non-existing ids are ignored.
      *
-     * @return Collection<object> list of documents that where found with the $ids and
-     *                            if specified the $className
+     * @phpstan-param class-string<T>|null $className
+     *
+     * @return array<object> list of documents that where found with the $ids and
+     *                       if specified the $className
+     *
+     * @phpstan-return array<T>
+     *
+     * @template T of object
      */
-    public function findMany(?string $className, array $ids): Collection;
+    public function findMany(?string $className, array $ids): array;
 
     /**
      * Load the document from the content repository in the given language.
@@ -161,12 +172,18 @@ public function findMany(?string $className, array $ids): Collection;
      * @param string      $locale    The language to try to load
      * @param bool        $fallback  Set to true if the language fallback mechanism should be used
      *
+     * @phpstan-param class-string<T>|null $className
+     *
      * @return object|null the translated document or null if not found
      *
+     * @phpstan-return T|null
+     *
      * @throws MissingTranslationException if $fallback is false and the
      *                                     translation was not found
      * @throws PHPCRException              if $className is specified and does not match
      *                                     the class of the document that was found at $id
+     *
+     * @template T of object
      */
     public function findTranslation(?string $className, string $id, string $locale, bool $fallback = true): ?object;
 
@@ -234,8 +251,16 @@ public function createPhpcrQueryBuilder(): PhpcrQueryBuilder;
      * @param QueryInterface $query           the query instance as acquired through createPhpcrQuery()
      * @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
+     *
+     * @phpstan-param class-string<T>|null $className
+     *
+     * @return array<object>
+     *
+     * @phpstan-return array<T>
+     *
+     * @template T of object
      */
-    public function getDocumentsByPhpcrQuery(QueryInterface $query, ?string $className = null, ?string $primarySelector = null): Collection;
+    public function getDocumentsByPhpcrQuery(QueryInterface $query, ?string $className = null, ?string $primarySelector = null): array;
 
     /**
      * Bind the translatable fields of the document in the specified locale.
@@ -245,8 +270,12 @@ public function getDocumentsByPhpcrQuery(QueryInterface $query, ?string $classNa
      * @param object $document the document to persist a translation of
      * @param string $locale   the locale this document currently has
      *
+     * @phpstan-param T $document
+     *
      * @throws InvalidArgumentException if $document is not an object or not managed
      * @throws PHPCRException           if the document is not translatable
+     *
+     * @template T of object
      */
     public function bindTranslation(object $document, string $locale): void;
 
@@ -256,7 +285,11 @@ public function bindTranslation(object $document, string $locale): void;
      * @param object $document the document to persist a translation of
      * @param string $locale   the locale this document currently has
      *
+     * @phpstan-param T $document
+     *
      * @throws InvalidArgumentException if $document is not an object
+     *
+     * @template T of object
      */
     public function removeTranslation(object $document, string $locale): void;
 
@@ -267,10 +300,14 @@ public function removeTranslation(object $document, string $locale): void;
      * @param object $document         The document to get the locales for
      * @param bool   $includeFallbacks Whether to include the available language fallbacks
      *
+     * @phpstan-param T $document
+     *
      * @return string[] All locales existing for this particular document
      *
      * @throws MissingTranslationException if the document is not translatable
      * @throws InvalidArgumentException    if $document is not an object
+     *
+     * @template T of object
      */
     public function getLocalesFor(object $document, bool $includeFallbacks): array;
 
@@ -279,6 +316,10 @@ public function getLocalesFor(object $document, bool $includeFallbacks): array;
      *
      * To be translatable, it needs a translation strategy and have at least
      * one translated field.
+     *
+     * @phpstan-param T $document
+     *
+     * @template T of object
      */
     public function isDocumentTranslatable(object $document): bool;
 
@@ -293,7 +334,11 @@ public function isDocumentTranslatable(object $document): bool;
      * @param object $document   An already registered document
      * @param string $targetPath The target path including the nodename
      *
+     * @phpstan-param T $document
+     *
      * @throws InvalidArgumentException if $document is not an object
+     *
+     * @template T of object
      */
     public function move(object $document, string $targetPath): void;
 
@@ -309,7 +354,11 @@ public function move(object $document, string $targetPath): void;
      * @param string $targetName The nodename of the target of the reordering
      * @param bool   $before     Whether to move before or after the target
      *
+     * @phpstan-param T $document
+     *
      * @throws InvalidArgumentException if $document is not an object
+     *
+     * @template T of object
      */
     public function reorder(object $document, string $srcName, string $targetName, bool $before): void;
 
@@ -326,9 +375,13 @@ public function reorder(object $document, string $srcName, string $targetName, b
      * @param int               $fetchDepth Optional fetch depth
      * @param string|null       $locale     The locale to use during the loading of this collection
      *
+     * @phpstan-param T $document
+     *
      * @return ChildrenCollection collection of child documents
      *
      * @throws InvalidArgumentException if $document is not an object
+     *
+     * @template T of object
      */
     public function getChildren(object $document, array|string|null $filter = null, int $fetchDepth = -1, ?string $locale = null): ChildrenCollection;
 
@@ -350,7 +403,11 @@ public function getChildren(object $document, array|string|null $filter = null,
      * @param string|null $locale   The locale to use during the loading of this collection
      * @param string|null $refClass Class the referrer document must be instanceof
      *
+     * @phpstan-param T $document
+     *
      * @throws InvalidArgumentException if $document is not an object
+     *
+     * @template T of object
      */
     public function getReferrers(object $document, ?string $type = null, ?string $name = null, ?string $locale = null, ?string $refClass = null): ReferrersCollection;
 
@@ -362,7 +419,11 @@ public function getReferrers(object $document, ?string $type = null, ?string $na
      * has its identifier populated. Otherwise a proxy is returned that automatically
      * loads itself on first access.
      *
+     * @phpstan-param T|string $id
+     *
      * @return mixed|object the document reference
+     *
+     * @template T of object
      */
     public function getReference(string $documentName, object|string $id): mixed;
 
@@ -375,16 +436,24 @@ public function getReference(string $documentName, object|string $id): mixed;
      *
      * The document is made read only until you call checkout again.
      *
+     * @phpstan-param T $document
+     *
      * @throws InvalidArgumentException if $document is not managed
      *
      * @see checkpoint
+     *
+     * @template T of object
      */
     public function checkin(object $document): void;
 
     /**
      * Make a checked in document writable again.
      *
+     * @phpstan-param T $document
+     *
      * @throws InvalidArgumentException if $document is not managed
+     *
+     * @template T of object
      */
     public function checkout(object $document): void;
 
@@ -393,7 +462,11 @@ public function checkout(object $document): void;
      *
      * A new version is created and the writable document stays in checked out state
      *
+     * @phpstan-param T $document
+     *
      * @throws InvalidArgumentException if $document is not managed
+     *
+     * @template T of object
      */
     public function checkpoint(object $document): void;
 
@@ -410,7 +483,11 @@ public function checkpoint(object $document): void;
      *                                identifiers. If true, existing documents with the identical
      *                                identifier will be replaced, otherwise an exception is thrown.
      *
-     *@see findVersionByName
+     * @phpstan-param T $documentVersion
+     *
+     * @see findVersionByName
+     *
+     * @template T of object
      */
     public function restoreVersion(object $documentVersion, bool $removeExisting = true): void;
 
@@ -422,7 +499,11 @@ public function restoreVersion(object $documentVersion, bool $removeExisting = t
      *
      * @param object $documentVersion The version document as returned by findVersionByName
      *
+     * @phpstan-param T $documentVersion
+     *
      * @throws RepositoryException when trying to remove the root version or the last version
+     *
+     * @template T of object
      */
     public function removeVersion(object $documentVersion): void;
 
@@ -434,10 +515,13 @@ public function removeVersion(object $documentVersion): void;
      * @param object $document the document of which to get the version history
      * @param int    $limit    an optional limit to only get the latest $limit information
      *
-     * @return array of <versionname> => array("name" => <versionname>, "labels" => <array of labels>, "created" => <DateTime>)
-     *               oldest version first
+     * @phpstan-param T $document
+     *
+     * @return array<string, array{name: string, labels: array<string>, created: \DateTimeInterface}> Array keys are the version name
      *
      * @throws InvalidArgumentException if $document is not an object
+     *
+     * @template T of object
      */
     public function getAllLinearVersions(object $document, int $limit = -1): array;
 
@@ -451,10 +535,16 @@ public function getAllLinearVersions(object $document, int $limit = -1): array;
      * @param string $id          Id of the document
      * @param string $versionName The version name as given by getLinearPredecessors
      *
+     * @phpstan-param class-string<T>|null $className
+     *
      * @return object|null The detached document or null if the document is not found
      *
+     * @phpstan-return T|null
+     *
      * @throws UnsupportedRepositoryOperationException if the implementation does not support versioning
      * @throws InvalidArgumentException                if there is a document with $id but no version with $name
+     *
+     * @template T of object
      */
     public function findVersionByName(?string $className, string $id, string $versionName): ?object;
 
@@ -476,8 +566,12 @@ public function getUnitOfWork(): UnitOfWork;
      * @param object|array|null $document Optionally limit to a specific
      *                                    document or an array of documents
      *
+     * @phpstan-param T|array|null $document
+     *
      * @throws InvalidArgumentException if $document is neither null nor a
      *                                  document or an array of documents
+     *
+     * @template T of object
      */
     public function flush(object|array|null $document = null): void;
 
@@ -491,8 +585,12 @@ public function close(): void;
     /**
      * Return the node of the given object.
      *
+     * @phpstan-param T $document
+     *
      * @throws PHPCRException           if $document is not managed
      * @throws InvalidArgumentException if $document is not an object
+     *
+     * @template T of object
      */
     public function getNodeForDocument(object $document): NodeInterface;
 
@@ -501,7 +599,11 @@ public function getNodeForDocument(object $document): NodeInterface;
      *
      * @param object $document A managed document
      *
+     * @phpstan-param T $document
+     *
      * @throws PHPCRException if $document is not managed
+     *
+     * @template T of object
      */
     public function getDocumentId(object $document): ?string;
 }
diff --git a/lib/Doctrine/ODM/PHPCR/DocumentRepository.php b/lib/Doctrine/ODM/PHPCR/DocumentRepository.php
index c70cf76a0..b85000391 100644
--- a/lib/Doctrine/ODM/PHPCR/DocumentRepository.php
+++ b/lib/Doctrine/ODM/PHPCR/DocumentRepository.php
@@ -2,13 +2,13 @@
 
 namespace Doctrine\ODM\PHPCR;
 
-use Doctrine\Common\Collections\Collection;
 use Doctrine\Common\Proxy\Proxy;
 use Doctrine\ODM\PHPCR\Exception\InvalidArgumentException;
 use Doctrine\ODM\PHPCR\Mapping\ClassMetadata;
 use Doctrine\ODM\PHPCR\Query\Builder\ConstraintFactory;
 use Doctrine\ODM\PHPCR\Query\Builder\QueryBuilder;
 use Doctrine\ODM\PHPCR\Query\Query;
+use Doctrine\ODM\PHPCR\Query\QueryException;
 use Doctrine\Persistence\ObjectRepository;
 use PHPCR\Query\QOM\QueryObjectModelConstantsInterface as Constants;
 
@@ -21,6 +21,10 @@
  *
  * @author Jordi Boggiano <j.boggiano@seld.be>
  * @author Pascal Helfenstein <nicam@nicam.ch>
+ *
+ * @template T of object
+ *
+ * @template-implements ObjectRepository<T>
  */
 class DocumentRepository implements ObjectRepository
 {
@@ -43,6 +47,8 @@ public function __construct(
      * The id may either be a PHPCR path or UUID
      *
      * @param string $id document id
+     *
+     * @phpstan-return T
      */
     public function find($id): ?object
     {
@@ -55,16 +61,20 @@ public function find($id): ?object
      * The ids may either be PHPCR paths or UUID's, but all must be of the same type
      *
      * @param string[] $ids document ids
+     *
+     * @phpstan-return list<T>
      */
-    public function findMany(array $ids): Collection
+    public function findMany(array $ids): array
     {
         return $this->dm->findMany($this->className, $ids);
     }
 
     /**
      * Finds all documents in the repository.
+     *
+     * @phpstan-return list<T>
      */
-    public function findAll(): Collection
+    public function findAll(): array
     {
         return $this->findBy([]);
     }
@@ -76,9 +86,13 @@ public function findAll(): Collection
      * an InvalidArgumentException if certain values of the sorting or limiting details are
      * not supported.
      *
-     * @return Collection the objects matching the criteria
+     * @return array<object> the documents matching the criteria
+     *
+     * @phpstan-return list<T>
+     *
+     * @throws QueryException
      */
-    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): array
     {
         $qb = $this->createQueryBuilder('a');
 
@@ -126,7 +140,7 @@ public function findBy(array $criteria, ?array $orderBy = null, ?int $limit = nu
             }
         }
 
-        return $qb->getQuery()->execute();
+        return $qb->getQuery()->execute()->toArray();
     }
 
     /**
@@ -150,16 +164,22 @@ protected function constraintField(ConstraintFactory $where, string $field, mixe
      *
      * @return object|null The first document matching the criteria or null if
      *                     none found
+     *
+     * @phpstan-return T
+     *
+     * @throws QueryException
      */
     public function findOneBy(array $criteria): ?object
     {
         $documents = $this->findBy($criteria, null, 1);
 
-        return $documents->isEmpty() ? null : $documents->first();
+        return \count($documents) ? null : reset($documents);
     }
 
     /**
      * Refresh a document with the data from PHPCR.
+     *
+     * @phpstan-param T $document
      */
     public function refresh(object $document): void
     {
@@ -173,6 +193,8 @@ public function refreshDocumentForProxy(Proxy $document): void
 
     /**
      * Get the document class name this repository is for.
+     *
+     * @phpstan-return class-string<T>
      */
     public function getClassName(): string
     {
diff --git a/lib/Doctrine/ODM/PHPCR/Mapping/ClassMetadata.php b/lib/Doctrine/ODM/PHPCR/Mapping/ClassMetadata.php
index 2312aebd2..c8722d19d 100644
--- a/lib/Doctrine/ODM/PHPCR/Mapping/ClassMetadata.php
+++ b/lib/Doctrine/ODM/PHPCR/Mapping/ClassMetadata.php
@@ -102,7 +102,7 @@ class ClassMetadata implements ClassMetadataInterface
     /**
      * READ-ONLY: The name of the document class that is stored in the phpcr:class property.
      */
-    public ?string $name;
+    public string $name;
 
     /**
      * READ-ONLY: The namespace the document class is contained in.
@@ -1160,7 +1160,7 @@ public function isIdGeneratorNone(): bool
         return self::GENERATOR_TYPE_NONE === $this->idGenerator;
     }
 
-    public function getName(): ?string
+    public function getName(): string
     {
         return $this->name;
     }
@@ -1294,25 +1294,24 @@ public function getAssociationNames(): array
 
     /**
      * PHPCR-ODM uses integer codes for relation types.
-     *
-     * @return int|string|null
      */
-    public function getTypeOfField($fieldName)
+    public function getTypeOfField($fieldName): ?string
     {
+        // TODO: need to make sure our types are strings not int
         return $this->mappings[$fieldName]['type'] ?? null;
     }
 
-    public function getAssociationTargetClass($fieldName): ?string
+    public function getAssociationTargetClass($assocName): ?string
     {
-        if (empty($this->mappings[$fieldName]['targetDocument'])) {
+        if (empty($this->mappings[$assocName]['targetDocument'])) {
             throw new MappingException(sprintf(
                 'Association name expected, "%s" is not an association in "%s".',
-                $fieldName,
+                $assocName,
                 $this->name
             ));
         }
 
-        return $this->mappings[$fieldName]['targetDocument'];
+        return $this->mappings[$assocName]['targetDocument'];
     }
 
     public function getAssociationMappedByTargetField($assocName): string
@@ -1338,7 +1337,7 @@ public function isAssociationInverseSide($assocName): bool
      *
      * @return string|bool class name if the field is inherited, FALSE otherwise
      */
-    public function isInheritedField(string $fieldName)
+    public function isInheritedField(string $fieldName): bool|string
     {
         return $this->inheritedFields[$fieldName] ?? false;
     }
@@ -1571,10 +1570,8 @@ public function getIdentifierValue(object $document): string
      *
      * If there is no identifier mapped, returns an empty array as per the
      * specification.
-     *
-     * @param object $document
      */
-    public function getIdentifierValues($document): array
+    public function getIdentifierValues(object $document): array
     {
         try {
             return [$this->identifier => $this->getIdentifierValue($document)];
diff --git a/lib/Doctrine/ODM/PHPCR/Mapping/ClassMetadataFactory.php b/lib/Doctrine/ODM/PHPCR/Mapping/ClassMetadataFactory.php
index b174f613f..37851e535 100644
--- a/lib/Doctrine/ODM/PHPCR/Mapping/ClassMetadataFactory.php
+++ b/lib/Doctrine/ODM/PHPCR/Mapping/ClassMetadataFactory.php
@@ -21,7 +21,7 @@
  */
 class ClassMetadataFactory extends AbstractClassMetadataFactory
 {
-    protected $cacheSalt = '__PHPCRODMCLASSMETADATA';
+    protected string $cacheSalt = '__PHPCRODMCLASSMETADATA';
 
     private DocumentManagerInterface $dm;
     private ?MappingDriver $driver;
diff --git a/lib/Doctrine/ODM/PHPCR/Query/Query.php b/lib/Doctrine/ODM/PHPCR/Query/Query.php
index d29bad155..49c5fcca7 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 $hydrationMode = null): Collection|QueryResultInterface
     {
         if (!empty($parameters)) {
             $this->setParameters($parameters);
diff --git a/tests/Doctrine/Tests/ODM/PHPCR/Functional/DocumentRepositoryTest.php b/tests/Doctrine/Tests/ODM/PHPCR/Functional/DocumentRepositoryTest.php
index 4a90b8c0c..d2fa084c6 100644
--- a/tests/Doctrine/Tests/ODM/PHPCR/Functional/DocumentRepositoryTest.php
+++ b/tests/Doctrine/Tests/ODM/PHPCR/Functional/DocumentRepositoryTest.php
@@ -93,7 +93,7 @@ public function testLoadMany(): void
         // read second document into memory
         $usersRepository->find($user2->id);
         $users = $usersRepository->findMany([$user1->id, $user2->id]);
-        $this->assertEquals('/functional/beberlei', $users->key(), 'Documents are not returned in the order they were requested');
+        $this->assertEquals('/functional/beberlei', array_keys($users)[0], 'Documents are not returned in the order they were requested');
     }
 
     public function testFindBy(): void
diff --git a/tests/Doctrine/Tests/ODM/PHPCR/Functional/ReferenceTest.php b/tests/Doctrine/Tests/ODM/PHPCR/Functional/ReferenceTest.php
index f564a0f46..52763181e 100644
--- a/tests/Doctrine/Tests/ODM/PHPCR/Functional/ReferenceTest.php
+++ b/tests/Doctrine/Tests/ODM/PHPCR/Functional/ReferenceTest.php
@@ -108,7 +108,7 @@ public function testFindByUUID(): void
         $this->assertInstanceOf($this->referencedType, $document);
 
         $documents = $this->dm->findMany($this->referencedType, [$node->getIdentifier()]);
-        $this->assertInstanceOf($this->referencedType, $documents->first());
+        $this->assertInstanceOf($this->referencedType, reset($documents));
     }
 
     public function testCreateByPath(): void
diff --git a/tests/Doctrine/Tests/ODM/PHPCR/Functional/UnitOfWorkTest.php b/tests/Doctrine/Tests/ODM/PHPCR/Functional/UnitOfWorkTest.php
index 39aefe861..9ff3a38bf 100644
--- a/tests/Doctrine/Tests/ODM/PHPCR/Functional/UnitOfWorkTest.php
+++ b/tests/Doctrine/Tests/ODM/PHPCR/Functional/UnitOfWorkTest.php
@@ -241,8 +241,8 @@ public function testFetchingMultipleHierarchicalObjectsWithChildIdFirst(): void
 
         /* @var $child ParentTestObj */
         /* @var $parent ParentTestObj */
-        $child = $documents->first();
-        $parent = $documents->last();
+        $child = reset($documents);
+        $parent = end($documents);
 
         $this->assertSame($child->parent, $parent);
         $this->assertSame('parent', $parent->nodename);