WebSocketServlet in a WAR-file: Bad character 13 for SelectChannelEndPoint - servlets

Question

On Mac with Oracle java "1.8.0_45" I have create a Jetty base dir with:
# java -jar /Users/afarber/jetty-distribution-9.3.10.v20160621/start.jar jetty.home=/Users/afarber/jetty-distribution-9.3.10.v20160621 jetty.base=/Users/afarber/jetty-base --add-to-startd=http,servlet,webapp,resources,ext,fcgi,websocket,proxy-protocol,deploy
INFO: ext initialised in ${jetty.base}/start.d/ext.ini
INFO: resources initialised in ${jetty.base}/start.d/resources.ini
INFO: server initialised (transitively) in ${jetty.base}/start.d/server.ini
INFO: http initialised in ${jetty.base}/start.d/http.ini
INFO: servlet initialised in ${jetty.base}/start.d/servlet.ini
INFO: fcgi initialised in ${jetty.base}/start.d/fcgi.ini
INFO: proxy-protocol initialised in ${jetty.base}/start.d/proxy-protocol.ini
INFO: webapp initialised in ${jetty.base}/start.d/webapp.ini
INFO: websocket initialised in ${jetty.base}/start.d/websocket.ini
MKDIR: ${jetty.base}/lib
MKDIR: ${jetty.base}/lib/ext
MKDIR: ${jetty.base}/resources
MKDIR: ${jetty.base}/webapps
INFO: Base directory was modified
Then I have put $JETTY_BASE/webapps/ws-servlet-0.1-SNAPSHOT.war produced by the very simple Maven project out of -
WsServlet.java
public class WsServlet extends WebSocketServlet
{
#Override
public void configure(WebSocketServletFactory factory) {
factory.register(EchoListener.class);
}
}
EchoListener.java
public class EchoListener implements WebSocketListener {
private static final Logger LOG = Log.getLogger(EchoListener.class);
private Session mSession;
#Override
public void onWebSocketConnect(Session session) {
LOG.info("onWebSocketConnect {}", session);
mSession = session;
}
#Override
public void onWebSocketText(String message) {
LOG.info("onWebSocketText {}", message);
if (mSession != null && mSession.isOpen()) {
mSession.getRemote().sendString("ECHO: " + message, null);
}
}
}
Finally I have created the $JETTY_BASE/webapps/ws.xml file pointing to the WAR-file:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN"
"http://www.eclipse.org/jetty/configure_9_0.dtd">
<Configure class="org.eclipse.jetty.webapp.WebAppContext">
<Set name="contextPath">/ws</Set>
<Set name="war"><SystemProperty name="jetty.base"/>/webapps/ws-servlet-0.1-SNAPSHOT.war</Set>
</Configure>
When I start Jetty and then connect to it using simple JavaScript code in browser var ws = new WebSocket("//127.0.0.1:8080/ws"); or the Simple Web Socket Client extension for Chrome the error comes:
# java -Dorg.eclipse.jetty.LEVEL=DEBUG -jar /Users/afarber/jetty-distribution-9.3.10.v20160621/start.jar jetty.base=/Users/afarber/jetty-base
....
WARN:oejs.ProxyConnectionFactory:qtp1993134103-12: Bad character 13 for SelectChannelEndPoint#26ba5622{/127.0.0.1:49883<->8080,Open,in,out,-,-,0/30000,ProxyConnection#49376d8e}{io=1/0,kio=1,kro=1}
Here is the full Jetty log, what have I missed here please?
UPDATE:
I have also tried connecting to ws://127.0.0.1:8080/ws-servlet-0.1-SNAPSHOT and tried adding annotations like #WebServlet(name = "WsServlet", urlPatterns = { "/ws" })- but that does not help. Also I have tried the older version 9.3.9.v20160517.
UPDATE 2:
Is the root cause the PROXY Protocol, which I have to use at my production server, because I offload SSL and normal connections to HAProxy? From the doc I read that 13 is sent as the first byte.
UPDATE 3:
The problem has been solved by adding a trailing slash: ws://127.0.0.1:8080/ws/