diff --git a/.phpstan.neon b/.phpstan.neon
index e4fa0be..497960f 100644
--- a/.phpstan.neon
+++ b/.phpstan.neon
@@ -14,33 +14,53 @@ parameters:
 	scanDirectories:
 		- vendor
 
+	treatPhpDocTypesAsCertain: false
+
 	ignoreErrors:
 		-
-			message: "#^Property Art4\\\\JsonApiClient\\\\V1\\\\ResourceNull\\:\\:\\$data is never read, only written\\.$#"
+			message: "#^Constructor of class Art4\\\\JsonApiClient\\\\V1\\\\ResourceNull has an unused parameter \\$data\\.$#"
 			count: 1
 			path: src/V1/ResourceNull.php
+			# parameter is required by Art4\JsonApiClient\Element
 
 		-
-			message: "#^Property Art4\\\\JsonApiClient\\\\V1\\\\ResourceNull\\:\\:\\$manager is never read, only written\\.$#"
+			message: "#^Constructor of class Art4\\\\JsonApiClient\\\\V1\\\\ResourceNull has an unused parameter \\$manager\\.$#"
 			count: 1
 			path: src/V1/ResourceNull.php
+			# parameter is required by Art4\JsonApiClient\Element
 
 		-
-			message: "#^Property Art4\\\\JsonApiClient\\\\V1\\\\ResourceNull\\:\\:\\$parent is never read, only written\\.$#"
+			message: "#^Constructor of class Art4\\\\JsonApiClient\\\\V1\\\\ResourceNull has an unused parameter \\$parent\\.$#"
 			count: 1
 			path: src/V1/ResourceNull.php
+			# parameter is required by Art4\JsonApiClient\Element
 
 		-
 			message: "#^Constructor of an anonymous class has an unused parameter \\$data\\.$#"
 			count: 1
 			path: tests/BC/ElementTest.php
+			# parameter is required by Art4\JsonApiClient\Element
 
 		-
 			message: "#^Constructor of an anonymous class has an unused parameter \\$manager\\.$#"
 			count: 1
 			path: tests/BC/ElementTest.php
+			# parameter is required by Art4\JsonApiClient\Element
 
 		-
 			message: "#^Constructor of an anonymous class has an unused parameter \\$parent\\.$#"
 			count: 1
 			path: tests/BC/ElementTest.php
+			# parameter is required by Art4\JsonApiClient\Element
+
+		-
+			message: "#^Parameter \\#1 \\$key of method Art4\\\\JsonApiClient\\\\V1\\\\ResourceNull\\:\\:has\\(\\) expects Art4\\\\JsonApiClient\\\\Helper\\\\AccessKey\\|int\\|string, array given\\.$#"
+			count: 1
+			path: tests/Unit/V1/ResourceNullTest.php
+			# We are providing an invalid parameter to test the deprecation message
+
+		-
+			message: "#^Parameter \\#1 \\$key of method Art4\\\\JsonApiClient\\\\V1\\\\ResourceNull\\:\\:has\\(\\) expects Art4\\\\JsonApiClient\\\\Helper\\\\AccessKey\\|int\\|string, stdClass given\\.$#"
+			count: 1
+			path: tests/Unit/V1/ResourceNullTest.php
+			# We are providing an invalid parameter to test the deprecation message
diff --git a/src/V1/ResourceNull.php b/src/V1/ResourceNull.php
index 3065002..f4bd600 100644
--- a/src/V1/ResourceNull.php
+++ b/src/V1/ResourceNull.php
@@ -19,11 +19,6 @@
  */
 final class ResourceNull implements Accessable, Element
 {
-    /** @var mixed */
-    private $data;
-    private Manager $manager;
-    private Accessable $parent;
-
     /**
      * Constructor
      *
@@ -33,9 +28,6 @@ final class ResourceNull implements Accessable, Element
      */
     public function __construct($data, Manager $manager, Accessable $parent)
     {
-        $this->data = $data;
-        $this->manager = $manager;
-        $this->parent = $parent;
     }
 
     /**
diff --git a/tests/Unit/Helper/AccessableTraitTest.php b/tests/Unit/Helper/AccessableTraitTest.php
index af512b3..cda7d40 100644
--- a/tests/Unit/Helper/AccessableTraitTest.php
+++ b/tests/Unit/Helper/AccessableTraitTest.php
@@ -9,12 +9,14 @@
 namespace Art4\JsonApiClient\Tests\Unit\Helper;
 
 use Art4\JsonApiClient\Helper\AccessableTrait;
+use Art4\JsonApiClient\Accessable;
 use PHPUnit\Framework\TestCase;
 
 class AccessableTraitTest extends TestCase
 {
     public function testHasWithObjectAsKeyTriggersException(): void
     {
+        /** @var Accessable */
         $resource = $this->getMockForTrait(AccessableTrait::class);
 
         // PHPUnit 10 compatible way to test trigger_error().
@@ -36,6 +38,7 @@ function ($errno, $errstr): bool {
 
     public function testHasWithArrayAsKeyTriggersException(): void
     {
+        /** @var Accessable */
         $resource = $this->getMockForTrait(AccessableTrait::class);
 
         // PHPUnit 10 compatible way to test trigger_error().