code: public static long getLastModified(String url) throws MalformedURLException {
  		HttpServletRequest request = getRequest();
  		// Get the context-relative path (resolves relative paths)
  		String resourcePath = ServletUtil.getAbsolutePath(
  			Dispatcher.getCurrentPagePath(request),
  			url
  		);
  		if(resourcePath.startsWith("/")) {
  			return LastModifiedServlet.getLastModified(
  				getServletContext(),
  				request,
  				resourcePath
  			);
  		}
  		return 0;
  	}
docs: Gets the lastModified or {@code 0} when not known.