@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
// If an If-Modified-Since header is ever provided, we always say
// not modified. This is because when there actually is a change,
// cache busting should occur.
UriStatus urlStatus = getUrlStatus(req);
if (req.getHeader("If-Modified-Since") != null &&
!"1".equals(req.getParameter("nocache")) &&
urlStatus == UriStatus.VALID_VERSIONED) {
resp.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
return;