code: func ParseMetadataHeader(header string) map[string]string {
  	meta := make(map[string]string)
  
  	for _, element := range strings.Split(header, ",") {
  		element := strings.TrimSpace(element)
  
  		parts := strings.Split(element, " ")
  
  		// Do not continue with this element if no key and value or presented
  		if len(parts) != 2 {
  			continue
  		}
  
  		// Ignore corrent element if the value is no valid base64
  		key := parts[0]
  		value, err := base64.StdEncoding.DecodeString(parts[1])
  		if err != nil {
  			continue
  		}
  
  		meta[key] = string(value)
  	}
  
  	return meta
  }
docs: // ParseMetadataHeader parses the Upload-Metadata header as defined in the
  // File Creation extension.
  // e.g. Upload-Metadata: name bHVucmpzLnBuZw==,type aW1hZ2UvcG5n