Fixed logic in AbstractApi::getSigner() (#755)

* Fixed logic in AbstractApi::getSigner()

* Added changelgo

Author: Nyholm

CHANGELOG.md

@@ -2,6 +2,12 @@
 
 ## NOT RELEASED
 
+## 1.4.2
+
+### Fixed
+
+- Fixed logic in `AbstractApi::getSigner()` when passing `@region` to an API operation
+
 ## 1.4.1
 
 ### Fixed

src/AbstractApi.php

@@ -224,7 +224,7 @@ protected function getEndpoint(string $uri, array $query, ?string $region): stri
     private function getSigner(?string $region)
     {
         /** @var string $region */
-        $region = $region ?? $this->configuration->isDefault('region') ? null : $this->configuration->get('region');
+        $region = $region ?? ($this->configuration->isDefault('region') ? null : $this->configuration->get('region'));
         if (!isset($this->signers[$region])) {
             $metadata = $this->getEndpointMetadata($region);
             $factories = $this->getSignerFactories();