metadata = make(map[string]string)

	for _, hdr := range mimesHeader {
		// Extract all query values.
		err = extractMetadataFromMime(ctx, hdr, metadata)
		if err != nil {
			return nil, err
		}
	}

	// Set content-type to default value if it is not set.
	if _, ok := metadata[strings.ToLower(xhttp.ContentType)]; !ok {