diff --git a/src/Util/AdminAclManipulator.php b/src/Util/AdminAclManipulator.php
index dc1e5da5aa..8b4a742746 100644
--- a/src/Util/AdminAclManipulator.php
+++ b/src/Util/AdminAclManipulator.php
@@ -18,7 +18,6 @@
 use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\Security\Acl\Domain\ObjectIdentity;
 use Symfony\Component\Security\Acl\Domain\RoleSecurityIdentity;
-use Symfony\Component\Security\Acl\Model\AclInterface;
 use Symfony\Component\Security\Acl\Model\MutableAclInterface;
 
 /**
@@ -28,13 +27,14 @@ final class AdminAclManipulator implements AdminAclManipulatorInterface
 {
     /**
      * @var string
+     * @phpstan-var class-string
      */
     private $maskBuilderClass;
 
     /**
-     * @param string $maskBuilderClass
+     * @phpstan-param class-string $maskBuilderClass
      */
-    public function __construct($maskBuilderClass)
+    public function __construct(string $maskBuilderClass)
     {
         $this->maskBuilderClass = $maskBuilderClass;
     }
@@ -69,17 +69,10 @@ public function configureAcls(OutputInterface $output, AdminInterface $admin): v
 
     public function addAdminClassAces(
         OutputInterface $output,
-        AclInterface $acl,
+        MutableAclInterface $acl,
         AclSecurityHandlerInterface $securityHandler,
         array $roleInformation = []
-    ) {
-        if (!$acl instanceof MutableAclInterface) {
-            throw new \TypeError(sprintf(
-                'Argument 2 passed to "%s()" must implement "%s".',
-                __METHOD__,
-                MutableAclInterface::class
-            ));
-        }
+    ): bool {
         if (\count($securityHandler->getAdminPermissions()) > 0) {
             $builder = new $this->maskBuilderClass();
 
diff --git a/src/Util/AdminAclManipulatorInterface.php b/src/Util/AdminAclManipulatorInterface.php
index d00b3d63a6..6b3aac967a 100644
--- a/src/Util/AdminAclManipulatorInterface.php
+++ b/src/Util/AdminAclManipulatorInterface.php
@@ -16,7 +16,7 @@
 use Sonata\AdminBundle\Admin\AdminInterface;
 use Sonata\AdminBundle\Security\Handler\AclSecurityHandlerInterface;
 use Symfony\Component\Console\Output\OutputInterface;
-use Symfony\Component\Security\Acl\Model\AclInterface;
+use Symfony\Component\Security\Acl\Model\MutableAclInterface;
 
 /**
  * @author Thomas Rabaix <thomas.rabaix@sonata-project.org>
@@ -26,17 +26,17 @@ interface AdminAclManipulatorInterface
     /**
      * Batch configure the ACLs for all objects handled by an Admin.
      */
-    public function configureAcls(OutputInterface $output, AdminInterface $admin);
+    public function configureAcls(OutputInterface $output, AdminInterface $admin): void;
 
     /**
      * Add the class ACE's to the admin ACL.
      *
-     * @return bool TRUE if admin class ACEs are added, FALSE if not
+     * @param array<string, string[]> $roleInformation
      */
     public function addAdminClassAces(
         OutputInterface $output,
-        AclInterface $acl,
+        MutableAclInterface $acl,
         AclSecurityHandlerInterface $securityHandler,
         array $roleInformation = []
-    );
+    ): bool;
 }
diff --git a/src/Util/AdminObjectAclData.php b/src/Util/AdminObjectAclData.php
index 12e5fc789c..344e70cd58 100644
--- a/src/Util/AdminObjectAclData.php
+++ b/src/Util/AdminObjectAclData.php
@@ -15,7 +15,6 @@
 
 use Sonata\AdminBundle\Admin\AdminInterface;
 use Sonata\AdminBundle\Security\Handler\AclSecurityHandlerInterface;
-use Symfony\Component\Form\Form;
 use Symfony\Component\Form\FormInterface;
 use Symfony\Component\Security\Acl\Domain\Acl;
 use Symfony\Component\Security\Acl\Model\MutableAclInterface;
@@ -30,7 +29,7 @@
 class AdminObjectAclData
 {
     /**
-     * @var array Permissions managed only by a OWNER
+     * @var string[] Permissions managed only by a OWNER
      */
     protected static $ownerPermissions = ['MASTER', 'OWNER'];
 
@@ -60,34 +59,37 @@ class AdminObjectAclData
     protected $masks = [];
 
     /**
-     * @var FormInterface
+     * @var FormInterface|null
      */
     protected $aclUsersForm;
 
     /**
-     * @var FormInterface
+     * @var FormInterface|null
      */
     protected $aclRolesForm;
 
     /**
-     * @var MutableAclInterface
+     * @var MutableAclInterface|null
      */
     protected $acl;
 
     /**
      * @var string
+     * @phpstan-var class-string
      */
     protected $maskBuilderClass;
 
     /**
-     * @param object $object
-     * @param string $maskBuilderClass
+     * @param \Traversable $aclUsers
+     * @param \Traversable|null $aclRoles
+     *
+     * @phpstan-param class-string $maskBuilderClass
      */
     public function __construct(
         AdminInterface $admin,
-        $object,
+        object $object,
         \Traversable $aclUsers,
-        $maskBuilderClass,
+        string $maskBuilderClass,
         ?\Traversable $aclRoles = null
     ) {
         $this->admin = $admin;
@@ -102,138 +104,79 @@ public function __construct(
         $this->updateMasks();
     }
 
-    /**
-     * Gets admin.
-     *
-     * @return AdminInterface
-     */
-    public function getAdmin()
+    public function getAdmin(): AdminInterface
     {
         return $this->admin;
     }
 
-    /**
-     * Gets object.
-     *
-     * @return object
-     */
-    public function getObject()
+    public function getObject(): object
     {
         return $this->object;
     }
 
-    /**
-     * Gets ACL users.
-     *
-     * @return \Traversable
-     */
-    public function getAclUsers()
+    public function getAclUsers(): \Traversable
     {
         return $this->aclUsers;
     }
 
-    /**
-     * Gets ACL roles.
-     *
-     * @return \Traversable
-     */
-    public function getAclRoles()
+    public function getAclRoles(): \Traversable
     {
         return $this->aclRoles;
     }
 
-    /**
-     * Sets ACL.
-     *
-     * @return AdminObjectAclData
-     */
-    public function setAcl(MutableAclInterface $acl)
+    public function setAcl(MutableAclInterface $acl): self
     {
         $this->acl = $acl;
 
         return $this;
     }
 
-    /**
-     * Gets ACL.
-     *
-     * @return MutableAclInterface
-     */
-    public function getAcl()
+    public function getAcl(): MutableAclInterface
     {
+        \assert($this->acl !== null);
+
         return $this->acl;
     }
 
-    /**
-     * Gets masks.
-     *
-     * @return array
-     */
-    public function getMasks()
+    public function getMasks(): array
     {
         return $this->masks;
     }
 
-    /**
-     * Sets ACL users form.
-     *
-     * @return AdminObjectAclData
-     */
-    public function setAclUsersForm(FormInterface $form)
+    public function setAclUsersForm(FormInterface $form): self
     {
         $this->aclUsersForm = $form;
 
         return $this;
     }
 
-    /**
-     * Gets ACL users form.
-     *
-     * @return FormInterface
-     */
-    public function getAclUsersForm()
+    public function getAclUsersForm(): FormInterface
     {
+        \assert($this->aclUsersForm !== null);
+
         return $this->aclUsersForm;
     }
 
-    /**
-     * Sets ACL roles form.
-     *
-     * @return AdminObjectAclData
-     */
-    public function setAclRolesForm(FormInterface $form)
+    public function setAclRolesForm(FormInterface $form): self
     {
         $this->aclRolesForm = $form;
 
         return $this;
     }
 
-    /**
-     * Gets ACL roles form.
-     *
-     * @return FormInterface
-     */
-    public function getAclRolesForm()
+    public function getAclRolesForm(): FormInterface
     {
+        \assert($this->aclRolesForm !== null);
+
         return $this->aclRolesForm;
     }
 
-    /**
-     * Gets permissions.
-     *
-     * @return array
-     */
-    public function getPermissions()
+    public function getPermissions(): array
     {
         return $this->getSecurityHandler()->getObjectPermissions();
     }
 
-    /**
-     * Get permissions that the current user can set.
-     *
-     * @return array
-     */
-    public function getUserPermissions()
+    public function getUserPermissions(): array
     {
         $permissions = $this->getPermissions();
 
@@ -249,28 +192,24 @@ public function getUserPermissions()
         return $permissions;
     }
 
-    public function getOwnerPermissions()
+    /**
+     * @return string[]
+     */
+    public function getOwnerPermissions(): array
     {
         return self::$ownerPermissions;
     }
 
     /**
      * Tests if the current user has the OWNER right.
-     *
-     * @return bool
      */
-    public function isOwner()
+    public function isOwner(): bool
     {
         // Only a owner can set MASTER and OWNER ACL
         return $this->admin->isGranted('OWNER', $this->object);
     }
 
-    /**
-     * Gets security handler.
-     *
-     * @return AclSecurityHandlerInterface
-     */
-    public function getSecurityHandler()
+    public function getSecurityHandler(): AclSecurityHandlerInterface
     {
         $securityHandler = $this->admin->getSecurityHandler();
         \assert($securityHandler instanceof AclSecurityHandlerInterface);
@@ -278,10 +217,7 @@ public function getSecurityHandler()
         return $securityHandler;
     }
 
-    /**
-     * @return array
-     */
-    public function getSecurityInformation()
+    public function getSecurityInformation(): array
     {
         return $this->getSecurityHandler()->buildSecurityInformation($this->admin);
     }
diff --git a/src/Util/AdminObjectAclManipulator.php b/src/Util/AdminObjectAclManipulator.php
index 9a9b440b1e..8128452f1e 100644
--- a/src/Util/AdminObjectAclManipulator.php
+++ b/src/Util/AdminObjectAclManipulator.php
@@ -15,7 +15,6 @@
 
 use Sonata\AdminBundle\Form\Type\AclMatrixType;
 use Symfony\Component\Form\Extension\Core\Type\FormType;
-use Symfony\Component\Form\Form;
 use Symfony\Component\Form\FormBuilderInterface;
 use Symfony\Component\Form\FormFactoryInterface;
 use Symfony\Component\Form\FormInterface;
@@ -42,36 +41,28 @@ class AdminObjectAclManipulator
      * @var FormFactoryInterface
      */
     protected $formFactory;
+
     /**
      * @var string
+     * @phpstan-var class-string
      */
     protected $maskBuilderClass;
 
     /**
-     * @param string $maskBuilderClass
+     * @phpstan-param class-string $maskBuilderClass
      */
-    public function __construct(FormFactoryInterface $formFactory, $maskBuilderClass)
+    public function __construct(FormFactoryInterface $formFactory, string $maskBuilderClass)
     {
         $this->formFactory = $formFactory;
         $this->maskBuilderClass = $maskBuilderClass;
     }
 
-    /**
-     * Gets mask builder class name.
-     *
-     * @return string
-     */
-    public function getMaskBuilderClass()
+    public function getMaskBuilderClass(): string
     {
         return $this->maskBuilderClass;
     }
 
-    /**
-     * Gets the ACL users form.
-     *
-     * @return FormInterface
-     */
-    public function createAclUsersForm(AdminObjectAclData $data)
+    public function createAclUsersForm(AdminObjectAclData $data): FormInterface
     {
         $aclValues = $data->getAclUsers();
         $formBuilder = $this->formFactory->createNamedBuilder(self::ACL_USERS_FORM_NAME, FormType::class);
@@ -81,12 +72,7 @@ public function createAclUsersForm(AdminObjectAclData $data)
         return $form;
     }
 
-    /**
-     * Gets the ACL roles form.
-     *
-     * @return FormInterface
-     */
-    public function createAclRolesForm(AdminObjectAclData $data)
+    public function createAclRolesForm(AdminObjectAclData $data): FormInterface
     {
         $aclValues = $data->getAclRoles();
         $formBuilder = $this->formFactory->createNamedBuilder(self::ACL_ROLES_FORM_NAME, FormType::class);
@@ -96,9 +82,6 @@ public function createAclRolesForm(AdminObjectAclData $data)
         return $form;
     }
 
-    /**
-     * Updates ACL users.
-     */
     public function updateAclUsers(AdminObjectAclData $data): void
     {
         $aclValues = $data->getAclUsers();
@@ -107,9 +90,6 @@ public function updateAclUsers(AdminObjectAclData $data): void
         $this->buildAcl($data, $form, $aclValues);
     }
 
-    /**
-     * Updates ACL roles.
-     */
     public function updateAclRoles(AdminObjectAclData $data): void
     {
         $aclValues = $data->getAclRoles();
@@ -119,7 +99,9 @@ public function updateAclRoles(AdminObjectAclData $data): void
     }
 
     /**
-     * Builds ACL.
+     * @param \Traversable<int|string, UserInterface|string> $aclValues
+     *
+     * @phpstan-param \Traversable<array-key, UserInterface|string> $aclValues
      */
     protected function buildAcl(AdminObjectAclData $data, FormInterface $form, \Traversable $aclValues): void
     {
@@ -175,7 +157,7 @@ protected function buildAcl(AdminObjectAclData $data, FormInterface $form, \Trav
                 }
             }
 
-            if ($ace) {
+            if (null !== $ace && null !== $index) {
                 $acl->updateObjectAce($index, $mask);
             } else {
                 $acl->insertObjectAce($securityIdentity, $mask);
@@ -186,11 +168,11 @@ protected function buildAcl(AdminObjectAclData $data, FormInterface $form, \Trav
     }
 
     /**
-     * Builds the form.
+     * @param \Traversable<int|string, UserInterface|string> $aclValues
      *
-     * @return FormInterface
+     * @phpstan-param \Traversable<array-key, UserInterface|string> $aclValues
      */
-    protected function buildForm(AdminObjectAclData $data, FormBuilderInterface $formBuilder, \Traversable $aclValues)
+    protected function buildForm(AdminObjectAclData $data, FormBuilderInterface $formBuilder, \Traversable $aclValues): FormInterface
     {
         // Retrieve object identity
         $objectIdentity = ObjectIdentity::fromDomainObject($data->getObject());
diff --git a/src/Util/FormBuilderIterator.php b/src/Util/FormBuilderIterator.php
index c7da9103d3..dface7ff43 100644
--- a/src/Util/FormBuilderIterator.php
+++ b/src/Util/FormBuilderIterator.php
@@ -20,23 +20,13 @@
  */
 final class FormBuilderIterator extends \RecursiveArrayIterator
 {
-    /**
-     * @var \ReflectionProperty
-     */
-    private static $reflection;
-
     /**
      * @var FormBuilderInterface
      */
     private $formBuilder;
 
     /**
-     * @var array
-     */
-    private $keys = [];
-
-    /**
-     * @var bool|string
+     * @var string
      */
     private $prefix;
 
@@ -46,13 +36,13 @@ final class FormBuilderIterator extends \RecursiveArrayIterator
     private $iterator;
 
     /**
-     * @param bool $prefix
+     * @param string|false $prefix
      */
     public function __construct(FormBuilderInterface $formBuilder, $prefix = false)
     {
         parent::__construct();
         $this->formBuilder = $formBuilder;
-        $this->prefix = $prefix ? $prefix : $formBuilder->getName();
+        $this->prefix = false !== $prefix ? $prefix : $formBuilder->getName();
         $this->iterator = new \ArrayIterator(self::getKeys($formBuilder));
     }
 
@@ -61,12 +51,12 @@ public function rewind(): void
         $this->iterator->rewind();
     }
 
-    public function valid()
+    public function valid(): bool
     {
         return $this->iterator->valid();
     }
 
-    public function key()
+    public function key(): string
     {
         $name = $this->iterator->current();
 
@@ -78,27 +68,27 @@ public function next(): void
         $this->iterator->next();
     }
 
-    public function current()
+    public function current(): FormBuilderInterface
     {
         return $this->formBuilder->get($this->iterator->current());
     }
 
-    public function getChildren()
+    public function getChildren(): self
     {
-        return new self($this->formBuilder->get($this->iterator->current()), $this->current());
+        return new self($this->formBuilder->get($this->iterator->current()));
     }
 
-    public function hasChildren()
+    public function hasChildren(): bool
     {
         return \count(self::getKeys($this->current())) > 0;
     }
 
     /**
-     * @static
+     * @return array<int|string, int|string>
      *
-     * @return array
+     * @phpstan-return array-key[]
      */
-    private static function getKeys(FormBuilderInterface $formBuilder)
+    private static function getKeys(FormBuilderInterface $formBuilder): array
     {
         return array_keys($formBuilder->all());
     }
diff --git a/src/Util/FormViewIterator.php b/src/Util/FormViewIterator.php
index 21b4954677..200b69911c 100644
--- a/src/Util/FormViewIterator.php
+++ b/src/Util/FormViewIterator.php
@@ -30,17 +30,17 @@ public function __construct(FormView $formView)
         $this->iterator = $formView->getIterator();
     }
 
-    public function getChildren()
+    public function getChildren(): self
     {
         return new self($this->current());
     }
 
-    public function hasChildren()
+    public function hasChildren(): bool
     {
         return \count($this->current()->children) > 0;
     }
 
-    public function current()
+    public function current(): FormView
     {
         return $this->iterator->current();
     }
@@ -50,12 +50,12 @@ public function next(): void
         $this->iterator->next();
     }
 
-    public function key()
+    public function key(): string
     {
         return $this->current()->vars['id'];
     }
 
-    public function valid()
+    public function valid(): bool
     {
         return $this->iterator->valid();
     }
diff --git a/src/Util/ObjectAclManipulator.php b/src/Util/ObjectAclManipulator.php
index b6047ec732..fee2048432 100644
--- a/src/Util/ObjectAclManipulator.php
+++ b/src/Util/ObjectAclManipulator.php
@@ -28,7 +28,9 @@ abstract class ObjectAclManipulator implements ObjectAclManipulatorInterface
      *
      * @throws \Exception
      *
-     * @return array [countAdded, countUpdated]
+     * @return array<int, int> [countAdded, countUpdated]
+     *
+     * @phpstan-return array{0: int, 1: int}
      */
     public function configureAcls(
         OutputInterface $output,
diff --git a/src/Util/ObjectAclManipulatorInterface.php b/src/Util/ObjectAclManipulatorInterface.php
index 91c54ee140..f6317a195f 100644
--- a/src/Util/ObjectAclManipulatorInterface.php
+++ b/src/Util/ObjectAclManipulatorInterface.php
@@ -32,5 +32,5 @@ public function batchConfigureAcls(
         OutputInterface $output,
         AdminInterface $admin,
         ?UserSecurityIdentity $securityIdentity = null
-    );
+    ): void;
 }