xhttp.AmzSignature:    true,
	xhttp.ContentEncoding: true,
	http.CanonicalHeaderKey(xhttp.AmzChecksumAlgo):   true,
	http.CanonicalHeaderKey(xhttp.AmzChecksumCRC32):  true,
	http.CanonicalHeaderKey(xhttp.AmzChecksumCRC32C): true,
	http.CanonicalHeaderKey(xhttp.AmzChecksumSHA1):   true,
	http.CanonicalHeaderKey(xhttp.AmzChecksumSHA256): true,
	http.CanonicalHeaderKey(xhttp.AmzChecksumMode):   true,
}

// Add policy conditionals.
const (

	nv := make(textproto.MIMEHeader, len(v))
	for k, kv := range v {
		// Canonicalize all headers, to remove any duplicates.
		nv[http.CanonicalHeaderKey(k)] = kv
	}

	// Save all supported headers.
	for _, supportedHeader := range supportedHeaders {
		value, ok := nv[http.CanonicalHeaderKey(supportedHeader)]
		if ok {
			if v, ok := replicationToInternalHeaders[supportedHeader]; ok {
				m[v] = strings.Join(value, ",")