code: public void addFilePart(final String fieldName, final InputStream stream, final String contentType)
          throws IOException
      {
          addFilePart(fieldName, stream, null, contentType);
      }
docs: Adds a upload file section to the request by stream
  @param fieldName name attribute in &lt;input type="file" name="..." /&gt;
  @param stream input stream of data to upload
  @param contentType content type of data
  @throws IOException if problems