[FSSDK-8940] Correct return type hints (#265)

* Add mixed return type to jsonserialize

* Add test for 8.2

* Rollback 8.2 tests and add suggested comments

* Fix comment

* Update copyright

Author: rafinutshaw-optimizely

src/Optimizely/OptimizelyUserContext.php

@@ -1,6 +1,6 @@
 <?php
 /**
- * Copyright 2021-2022, Optimizely
+ * Copyright 2021-2023, Optimizely
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -147,6 +147,9 @@ public function getOptimizely()
         return $this->optimizelyClient;
     }
 
+    /**
+     * @return mixed
+     */
     #[\ReturnTypeWillChange]
     public function jsonSerialize()
     {

src/Optimizely/UserProfile/UserProfileServiceInterface.php

@@ -1,6 +1,6 @@
 <?php
 /**
- * Copyright 2017, Optimizely Inc, and Contributors
+ * Copyright 2017, 2023, Optimizely Inc, and Contributors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,7 +23,7 @@ interface UserProfileServiceInterface
      *
      * @param $userId      string The ID of the user whose profile will be retrieved.
      *
-     * @return userProfile array  The user profile.
+     * @return array  The user profile.
      */
     public function lookup($userId);