src/Payum/Core/Storage/FilesystemStorage.php
protected function doFind($id)
    {
        if (isset($this->identityMap[$id])) {
            return $this->identityMap[$id];
        }

        if (file_exists($this->storageDir.'/payum-model-'.$id)) {
            return $this->identityMap[$id] = unserialize(file_get_contents($this->storageDir.'/payum-model-'.$id));
        }
    }
protected function doFind($id)
    {
        if (isset($this->identityMap[$id])) {
            return $this->identityMap[$id];
        }

        if (file_exists($this->storageDir.'/payum-model-'.$id)) {
            return $this->identityMap[$id] = unserialize(file_get_contents($this->storageDir.'/payum-model-'.$id));
        }
    }
{@inheritDoc}