diff --git a/Admin/Install/Navigation.php b/Admin/Install/Navigation.php
index cfab2dd..6eef587 100644
--- a/Admin/Install/Navigation.php
+++ b/Admin/Install/Navigation.php
@@ -36,7 +36,7 @@ class Navigation
      *
      * @since  1.0.0
      */
-    public static function install(string $path = null, DatabasePool $dbPool = null) : void
+    public static function install(string $path, DatabasePool $dbPool) : void
     {
         \Modules\Navigation\Admin\Installer::installExternal($dbPool, ['path' => __DIR__ . '/Navigation.install.json']);
     }
diff --git a/Controller/ApiController.php b/Controller/ApiController.php
index 9ccdaaf..4345fbe 100644
--- a/Controller/ApiController.php
+++ b/Controller/ApiController.php
@@ -18,7 +18,6 @@ use Modules\QA\Models\QAQuestionMapper;
 use phpOMS\Message\RequestAbstract;
 use phpOMS\Message\ResponseAbstract;
 
-
 /**
  * Task class.
  *
diff --git a/Controller/BackendController.php b/Controller/BackendController.php
index 4eaa2c5..6e10dd2 100644
--- a/Controller/BackendController.php
+++ b/Controller/BackendController.php
@@ -15,7 +15,9 @@ declare(strict_types=1);
 namespace Modules\QA\Controller;
 
 use Modules\QA\Models\QAQuestionMapper;
+
 use phpOMS\Asset\AssetType;
+use phpOMS\Contract\RenderableInterface;
 use phpOMS\Message\RequestAbstract;
 use phpOMS\Message\ResponseAbstract;
 
@@ -52,12 +54,12 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable
+     * @return RenderableInterface
      *
      * @since  1.0.0
      * @codeCoverageIgnore
      */
-    public function viewQADashboard(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewQADashboard(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
         $view->setTemplate('/Modules/QA/Theme/Backend/qa-dashboard');
@@ -74,12 +76,12 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable
+     * @return RenderableInterface
      *
      * @since  1.0.0
      * @codeCoverageIgnore
      */
-    public function viewQADoc(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewQADoc(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
         $view->setTemplate('/Modules/QA/Theme/Backend/qa-question');
@@ -95,12 +97,12 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable
+     * @return RenderableInterface
      *
      * @since  1.0.0
      * @codeCoverageIgnore
      */
-    public function viewQAQuestionCreate(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewQAQuestionCreate(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
         $view->setTemplate('/Modules/QA/Theme/Backend/qa-question-create');
diff --git a/Models/QAQuestionMapper.php b/Models/QAQuestionMapper.php
index cee92bd..e427e20 100644
--- a/Models/QAQuestionMapper.php
+++ b/Models/QAQuestionMapper.php
@@ -50,11 +50,6 @@ final class QAQuestionMapper extends DataMapperAbstract
      *
      * @var array<string, array<string, null|string>>
      * @since 1.0.0
-     */    /**
-     * Has many relation.
-     *
-     * @var array<string, array<string, string>>
-     * @since 1.0.0
      */
     protected static $hasMany = [
         'answers' => [