public HttpRequest part(final String name, final String filename,
      final String part) throws HttpRequestException {
    return part(name, filename, null, part);
  }
Write part of a multipart request to the request body

@param name
@param filename
@param part
@return this request
@throws HttpRequestException
lib/src/main/java/com/github/kevinsawicki/http/HttpRequest.java