minor #42247 [5.2] Add missing @return annotations (nicolas-grekas)

This PR was merged into the 5.2 branch.

Discussion
----------

[5.2] Add missing ``@return`` annotations

| Q             | A
| ------------- | ---
| Branch?       | 5.2
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       | -
| License       | MIT
| Doc PR        | -

Same as #42246 for 5.2

Commits
-------

7c10e093b8 [5.2] Add missing ``@return`` annotations

Author: nicolas-grekas

Response/AmpResponse.php

@@ -142,6 +142,9 @@ public function getInfo(string $type = null)
         return null !== $type ? $this->info[$type] ?? null : $this->info;
     }
 
+    /**
+     * @return array
+     */
     public function __sleep()
     {
         throw new \BadMethodCallException('Cannot serialize '.__CLASS__);

Response/CommonResponseTrait.php

@@ -127,6 +127,9 @@ public function toStream(bool $throw = true)
         return $stream;
     }
 
+    /**
+     * @return array
+     */
     public function __sleep()
     {
         throw new \BadMethodCallException('Cannot serialize '.__CLASS__);

Response/TraceableResponse.php

@@ -44,6 +44,9 @@ public function __construct(HttpClientInterface $client, ResponseInterface $resp
         $this->event = $event;
     }
 
+    /**
+     * @return array
+     */
     public function __sleep()
     {
         throw new \BadMethodCallException('Cannot serialize '.__CLASS__);