private function getPresignHeaders(array $headers)
    {
        $presignHeaders = [];
        $blacklist = $this->getHeaderBlacklist();
        foreach ($headers as $name => $value) {
            $lName = strtolower($name);
            if (!isset($blacklist[$lName])
                && $name !== self::AMZ_CONTENT_SHA256_HEADER
            ) {
                $presignHeaders[] = $lName;
            }
        }
        return $presignHeaders;
    }