fix php8.1 jsonserialize

Author: Rick-flashpoint

src/Model/Collection.php

@@ -43,7 +43,7 @@ public function addElement($element)
     /**
      * @return int
      */
-    public function count()
+    public function count(): int
     {
         return count($this->elements);
     }
@@ -55,7 +55,7 @@ public function count()
      * which is a value of any type other than a resource.
      * @since 5.4.0
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): mixed
     {
         if ($this->key !== null) {
             return [$this->key => $this->elements];

src/Model/Customer.php

@@ -235,7 +235,7 @@ public function __toString(): string
      * which is a value of any type other than a resource.
      * @since 5.4.0
      */
-    function jsonSerialize()
+    function jsonSerialize(): mixed
     {
         $data = [
             'email_address' => $this->emailAddress,

src/Model/Order.php

@@ -321,7 +321,7 @@ public function addDetailsView(DetailsView $detailsView)
      * which is a value of any type other than a resource.
      * @since 5.4.0
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): mixed
     {
         $data = [
             'order_number' => $this->orderNumber,

src/Model/Order/DetailsView.php

@@ -106,7 +106,7 @@ public function setDateFormat(string $dateFormat)
      * which is a value of any type other than a resource.
      * @since 5.4.0
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): mixed
     {
         $data = ['display_as' => $this->displayAs];
 

src/Model/SearchResult.php

@@ -39,7 +39,7 @@ public function __construct(Collection $customerCollection, Collection $orderCol
      * which is a value of any type other than a resource.
      * @since 5.4.0
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): mixed
     {
         return [
             'customers' => $this->customerCollection,