diff --git a/src/Management/Model/DataSource.php b/src/Management/Model/DataSource.php
index 3f24b17..32d077a 100644
--- a/src/Management/Model/DataSource.php
+++ b/src/Management/Model/DataSource.php
@@ -58,7 +58,7 @@ public static function createFromArray(array $data)
     /**
      * @return array
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         return [
             'type' => $this->type,
diff --git a/src/Management/Model/DataSourceOptionBigCommerce.php b/src/Management/Model/DataSourceOptionBigCommerce.php
index b4010a5..d46696b 100644
--- a/src/Management/Model/DataSourceOptionBigCommerce.php
+++ b/src/Management/Model/DataSourceOptionBigCommerce.php
@@ -33,7 +33,7 @@ public static function createFromArray(array $data)
     /**
      * @return string[]
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         return [
             'url' => $this->url,
diff --git a/src/Management/Model/DataSourceOptionEkm.php b/src/Management/Model/DataSourceOptionEkm.php
index 8e16201..d1bf67a 100644
--- a/src/Management/Model/DataSourceOptionEkm.php
+++ b/src/Management/Model/DataSourceOptionEkm.php
@@ -27,7 +27,7 @@ public static function createFromArray(array $data)
     /**
      * @return string[]
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         return [
             'url' => $this->url,
diff --git a/src/Management/Model/DataSourceOptionFile.php b/src/Management/Model/DataSourceOptionFile.php
index 5da25b4..547ba25 100644
--- a/src/Management/Model/DataSourceOptionFile.php
+++ b/src/Management/Model/DataSourceOptionFile.php
@@ -27,7 +27,7 @@ public static function createFromArray(array $data)
     /**
      * @return string[]
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         return [
             'url' => $this->url,
diff --git a/src/Management/Model/DataSourceOptionMagento.php b/src/Management/Model/DataSourceOptionMagento.php
index c0e0dea..692e482 100644
--- a/src/Management/Model/DataSourceOptionMagento.php
+++ b/src/Management/Model/DataSourceOptionMagento.php
@@ -19,7 +19,7 @@ public static function createFromArray(array $data)
     /**
      * @return string[]
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         return [
             'url' => $this->url
diff --git a/src/Management/Model/DataSourceOptionShopify.php b/src/Management/Model/DataSourceOptionShopify.php
index b7df260..a54e241 100644
--- a/src/Management/Model/DataSourceOptionShopify.php
+++ b/src/Management/Model/DataSourceOptionShopify.php
@@ -27,7 +27,7 @@ public static function createFromArray(array $data)
     /**
      * @return string[]
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         return [
             'url' => $this->url,
diff --git a/src/Management/Model/Index.php b/src/Management/Model/Index.php
index 5e0eb53..8f57b99 100644
--- a/src/Management/Model/Index.php
+++ b/src/Management/Model/Index.php
@@ -64,7 +64,7 @@ public static function createFromArray(array $data)
     /**
      * @return array
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         return [
             'name' => $this->name,
diff --git a/src/Management/Model/Item.php b/src/Management/Model/Item.php
index 4d88835..9c37329 100644
--- a/src/Management/Model/Item.php
+++ b/src/Management/Model/Item.php
@@ -88,7 +88,7 @@ public static function createFromArray(array $data)
     /**
      * @return array
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         return array_merge([
             'id' => $this->id,
diff --git a/src/Management/Model/SearchEngine.php b/src/Management/Model/SearchEngine.php
index 68bd394..d2a53d4 100644
--- a/src/Management/Model/SearchEngine.php
+++ b/src/Management/Model/SearchEngine.php
@@ -204,7 +204,7 @@ public function isHasGrouping()
     /**
      * @return array
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         return [
             'language' => $this->language,