add AbstractProvider::prepareAccessTokenResult for additional token response prep

src/Provider/AbstractProvider.php

@@ -215,11 +215,24 @@ abstract class AbstractProvider implements ProviderInterface
             // @codeCoverageIgnoreEnd
         }
 
-        $this->setResultUid($result);
+        $result = $this->prepareAccessTokenResult($result);
 
         return $grant->handleResponse($result);
     }
 
+    /**
+     * Prepare the access token response for the grant. Custom mapping of
+     * expirations, etc should be done here.
+     *
+     * @param  array $result
+     * @return array
+     */
+    protected function prepareAccessTokenResult(array $result)
+    {
+        $this->setResultUid($result);
+        return $result;
+    }
+
     /**
      * Sets any result keys we've received matching our provider-defined uidKey to the key "uid".
      *