try (BufferedInputStream bis = new BufferedInputStream(inputSupplier.open(), BUFFER_SIZE)) {
            bis.mark(BUFFER_SIZE);
            XMLStreamReader xsr = XMLInputFactory.newFactory().createXMLStreamReader(bis);
            xsr.nextTag();
            String nsUri = xsr.getNamespaceURI();
            try (BufferedInputStream bis2 = reset(inputSupplier, bis)) {

   * @since 15.0 (in 14.0 with return type {@link BufferedInputStream})
   */
  public InputStream openBufferedStream() throws IOException {
    InputStream in = openStream();
    return (in instanceof BufferedInputStream)
        ? (BufferedInputStream) in
        : new BufferedInputStream(in);
  }

  /**