[4.4] Add missing @return annotations

Author: nicolas-grekas

Chunk/ErrorChunk.php

@@ -115,6 +115,9 @@ public function didThrow(): bool
         return $this->didThrow;
     }
 
+    /**
+     * @return array
+     */
     public function __sleep()
     {
         throw new \BadMethodCallException('Cannot serialize '.__CLASS__);

CurlHttpClient.php

@@ -362,6 +362,9 @@ public function reset()
         }
     }
 
+    /**
+     * @return array
+     */
     public function __sleep()
     {
         throw new \BadMethodCallException('Cannot serialize '.__CLASS__);

HttplugClient.php

@@ -218,6 +218,9 @@ public function createUri($uri): UriInterface
         throw new \LogicException(sprintf('You cannot use "%s()" as the "nyholm/psr7" package is not installed. Try running "composer require nyholm/psr7".', __METHOD__));
     }
 
+    /**
+     * @return array
+     */
     public function __sleep()
     {
         throw new \BadMethodCallException('Cannot serialize '.__CLASS__);