private function proxySave(CacheItemInterface $item, $deferred = false)
 {
     if ($item instanceof ItemDecorator) {
         return $this->decorated->{$deferred ? 'saveDeferred' : 'save'}($item->getDecorated());
     }
     throw new InvalidArgumentException('The provided cache item cannot' . ' be saved, as it did not originate from this cache.');
 }