code: private void writeNoContentResponse(final HttpServletResponse response) throws IOException {
  		response.setStatus(HttpServletResponse.SC_NO_CONTENT);
  		response.setContentType("image/gif");
  
  		final PrintWriter out = response.getWriter();
  		out.flush();
  	}
docs: Writes {@link HttpServletResponse#SC_NO_CONTENT} to response and flushes the stream.
  This means that only header and empty body will be returned to the caller script.
  
  @param response {@link HttpServletResponse}
  @throws IOException on errors