// Get signed headers.
	signedHeaders := strings.Join(headers, ";")

	// Get canonical query string.
	req.URL.RawQuery = strings.ReplaceAll(req.URL.Query().Encode(), "+", "%20")

	// Get canonical URI.
	canonicalURI := s3utils.EncodePath(req.URL.Path)

	// Get canonical request.
	// canonicalRequest =
	//  <HTTPMethod>\n
	//  <CanonicalURI>\n
	//  <CanonicalQueryString>\n
	//  <CanonicalHeaders>\n

// If input is nil an empty map is returned, not nil.
func cloneMSS(v map[string]string) map[string]string {
	r := make(map[string]string, len(v))
	for k, v := range v {
		r[k] = v
	}
	return r
}

// URI scheme constants.
const (
	httpScheme  = "http"
	httpsScheme = "https"
)

// nopCharsetConverter is a dummy charset convert which just copies input to output,