hashedPayload := req.Header.Get("x-amz-content-sha256")
	if hashedPayload == "" {
		return "", fmt.Errorf("Invalid hashed payload")
	}

	// Set x-amz-date.
	req.Header.Set("x-amz-date", currTime.Format(iso8601Format))

	// Get header map.
	headerMap := make(map[string][]string)
	for k, vv := range req.Header {
		// If request header key is not in ignored headers, then add it.

// empty string otherwise
func (rDate RetentionDate) MarshalXML(e *xml.Encoder, startElement xml.StartElement) error {
	if rDate.IsZero() {
		return nil
	}
	return e.EncodeElement(amztime.ISO8601Format(rDate.Time), startElement)
}

// ObjectRetention specified in
// https://docs.aws.amazon.com/AmazonS3/latest/API/API_PutObjectRetention.html
type ObjectRetention struct {

					srcInfo.UserDefined[strings.ToLower(xhttp.AmzObjectLockMode)] = string(retentionMode)
					srcInfo.UserDefined[strings.ToLower(xhttp.AmzObjectLockRetainUntilDate)] = amztime.ISO8601Format(retentionDate.UTC())
					srcInfo.UserDefined[ReservedMetadataPrefixLower+ObjectLockRetentionTimestamp] = srcTimestamp.UTC().Format(time.RFC3339Nano)
				}
			}
		} else {

	signedHeaders = append(signedHeaders, "expect")
	// expected header values.
	expectedHost := "play.min.io:9000"
	expectedContentSha256 := "1234abcd"
	expectedTime := UTCNow().Format(iso8601Format)
	expectedTransferEncoding := "gzip"
	expectedExpect := "100-continue"

	r, err := http.NewRequest(http.MethodGet, "http://play.min.io:9000", nil)
	if err != nil {

	if s3Err == ErrNone && retentionMode.Valid() {
		metadata[strings.ToLower(xhttp.AmzObjectLockMode)] = string(retentionMode)
		metadata[strings.ToLower(xhttp.AmzObjectLockRetainUntilDate)] = amztime.ISO8601Format(retentionDate.UTC())
	}
	if s3Err == ErrNone && legalHold.Status.Valid() {
		metadata[strings.ToLower(xhttp.AmzObjectLockLegalHold)] = string(legalHold.Status)
	}
	if s3Err != ErrNone {