@Override
    public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException {
        try (var stream = getServletContext().getResourceAsStream("/index.html")) {
            long len = stream.transferTo(res.getOutputStream());
            res.setContentLength(Math.toIntExact(len));
        }
        res.setContentType("text/html; charset=UTF-8");
        res.flushBuffer();
    }
@see javax.servlet.GenericServlet#service(javax.servlet.ServletRequest, javax.servlet.ServletResponse)
portal/war/wildfly/src/main/java/io/apiman/portal/AngularServlet.java