Jetty 11未检测到Servlets

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class HelloServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("text/html");
        resp.setStatus(HttpServletResponse.SC_OK);
        resp.getWriter().println("<h1>Hello from HelloServlet</h1>");
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE web-app PUBLIC
        "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
        "http://java.sun.com/dtd/web-app_2_3.dtd">

<web-app>
    <servlet>
        <servlet-name>HelloServlet</servlet-name>
        <servlet-class>HelloServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>HelloServlet</servlet-name>
        <url-pattern>/hello</url-pattern>
    </servlet-mapping>
</web-app>

import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.webapp.WebAppContext;

public class JettyServer {
    public static void main(String[] args) throws Exception {
        Server server = new Server(8080);
        WebAppContext webapp = new WebAppContext();
        webapp.setContextPath("/");
        webapp.setWar("path/to/your/webapp");
        server.setHandler(webapp);
        server.start();
        server.join();
    }
}