code: public Html loadHtmlTemplate(InputStream inputStream) throws IOException {
          StringBuilder sb = inputStreamToStringBuilder(inputStream);
          return loadHtmlTemplate(sb);
      }
docs: <p>
  load html template from input stream. inputStream will be closed at the
  end of this method. Doctype declaration on template will be deleted. If
  failed to parse error, returns null.
  </p>
  
  @param inputStream
  @return html tag object. If parse error, returns null.
  @throws IOException
  if inputStream is null.