185      * @param string $authUri optional auth uri
193         $authUri = null,  argument
203         $cached = $this->fetchAuthTokenFromCache($authUri);
217             $authUri,
222             $this->saveAuthTokenInCache($token, $authUri);
229      * @param string|null $authUri
232     private function fetchAuthTokenFromCache($authUri = null)  argument
242         $cacheKey = $authUri
243             ? $this->getFullCacheKey($authUri)
264      * @param string|null  $authUri
267     private function saveAuthTokenInCache($authToken, $authUri = null)  argument
272             $cacheKey = $authUri
273                 ? $this->getFullCacheKey($authUri)