Uploader/Uploader.php
private function checkKey($sourceKey)
    {
        if ($this->mountManager->has($sourceKey)) {
            return true;
        }

        if ($this->reconnectDistantFs($sourceKey)) {
            if ($this->mountManager->has($sourceKey)) {
                return true;
            }
        }

        return false;
    }
private function checkKey($sourceKey)
    {
        if ($this->mountManager->has($sourceKey)) {
            return true;
        }

        if ($this->reconnectDistantFs($sourceKey)) {
            if ($this->mountManager->has($sourceKey)) {
                return true;
            }
        }

        return false;
    }
Check the distant source key.

@param string $sourceKey
@return bool