diff --git a/src/ItemHydrator.php b/src/ItemHydrator.php
index 747ca1d..1daaaba 100644
--- a/src/ItemHydrator.php
+++ b/src/ItemHydrator.php
@@ -14,9 +14,9 @@
 class ItemHydrator
 {
     /**
-     * @var \Swis\JsonApi\Client\TypeMapper
+     * @var \Swis\JsonApi\Client\Interfaces\TypeMapperInterface
      */
-    private $typeMapper;
+    protected $typeMapper;
 
     /**
      * @param \Swis\JsonApi\Client\Interfaces\TypeMapperInterface $typeMapper
@@ -44,9 +44,9 @@ public function hydrate(ItemInterface $item, array $attributes): ItemInterface
 
     /**
      * @param \Swis\JsonApi\Client\Interfaces\ItemInterface $item
-     * @param array|null                                    $attributes
+     * @param array                                         $attributes
      */
-    protected function fill(ItemInterface $item, array $attributes = null)
+    protected function fill(ItemInterface $item, array $attributes)
     {
         $item->fill(array_diff_key($attributes, array_combine($item->getAvailableRelations(), $item->getAvailableRelations())));
     }
@@ -59,7 +59,7 @@ protected function fill(ItemInterface $item, array $attributes = null)
      *
      * @throws \Exception
      */
-    protected function fillRelations(ItemInterface $item, array $attributes = null)
+    protected function fillRelations(ItemInterface $item, array $attributes)
     {
         // Fill Relations
         foreach ($item->getAvailableRelations() as $availableRelation) {
diff --git a/src/JsonApi/Parser.php b/src/JsonApi/Parser.php
index d06f6c6..1d5a813 100644
--- a/src/JsonApi/Parser.php
+++ b/src/JsonApi/Parser.php
@@ -84,7 +84,6 @@ public function deserialize(string $json): DocumentInterface
      */
     private function getJsonApiDocument(string $json): Art4JsonApiDocumentInterface
     {
-        /** @var \Art4\JsonApiClient\DocumentInterface $jsonApiDocument */
         $jsonApiDocument = $this->manager->parse($json);
 
         if (!$jsonApiDocument instanceof Art4JsonApiDocumentInterface) {
@@ -109,20 +108,20 @@ protected function buildDataDocument(Art4JsonApiDocumentInterface $jsonApiDocume
         $allHydratedItems = new Collection();
         $allJsonApiItems = new Collection();
 
-        if ($data instanceof ResourceCollectionInterface) {
-            $collection = $this->hydrator->hydrateCollection($jsonApiDocument->get('data'));
-            $allHydratedItems = $allHydratedItems->concat($collection);
-            $allJsonApiItems = $allJsonApiItems->concat($jsonApiDocument->get('data')->asArray());
-
-            $document = new CollectionDocument();
-            $document->setData($collection);
-        } elseif ($data instanceof ResourceItemInterface) {
-            $item = $this->hydrator->hydrateItem($jsonApiDocument->get('data'));
+        if ($data instanceof ResourceItemInterface) {
+            $item = $this->hydrator->hydrateItem($data);
             $allHydratedItems->push($item);
-            $allJsonApiItems->push($jsonApiDocument->get('data'));
+            $allJsonApiItems->push($data);
 
             $document = new ItemDocument();
             $document->setData($item);
+        } elseif ($data instanceof ResourceCollectionInterface) {
+            $collection = $this->hydrator->hydrateCollection($data);
+            $allHydratedItems = $allHydratedItems->concat($collection);
+            $allJsonApiItems = $allJsonApiItems->concat(new Collection($data->asArray()));
+
+            $document = new CollectionDocument();
+            $document->setData($collection);
         } else {
             throw new \DomainException('Data is not Collection or Item');
         }
@@ -131,7 +130,7 @@ protected function buildDataDocument(Art4JsonApiDocumentInterface $jsonApiDocume
         if ($includedInDocument) {
             $included = $this->hydrator->hydrateCollection($includedInDocument);
             $allHydratedItems = $allHydratedItems->concat($included);
-            $allJsonApiItems = $allJsonApiItems->concat($includedInDocument->asArray());
+            $allJsonApiItems = $allJsonApiItems->concat(new Collection($includedInDocument->asArray()));
         }
 
         $this->hydrator->hydrateRelationships($allJsonApiItems, $allHydratedItems);
diff --git a/src/Providers/TypeMapperServiceProvider.php b/src/Providers/TypeMapperServiceProvider.php
index 54dbbd1..03422fa 100644
--- a/src/Providers/TypeMapperServiceProvider.php
+++ b/src/Providers/TypeMapperServiceProvider.php
@@ -2,10 +2,10 @@
 
 namespace Swis\JsonApi\Client\Providers;
 
-use Illuminate\Support\ServiceProvider;
+use Illuminate\Support\ServiceProvider as BaseServiceProvider;
 use Swis\JsonApi\Client\Interfaces\TypeMapperInterface;
 
-class TypeMapperServiceProvider extends ServiceProvider
+class TypeMapperServiceProvider extends BaseServiceProvider
 {
     /**
      * A list of class names implementing \Swis\JsonApi\Client\Interfaces\ItemInterface.