android webview can't get session when using target="_blank" with <a> link.

### Version 3.5.1 (maybe 3.5.0 included,not sure)


* vert.x core:

* vert.x web:


### Context


I used android webview to call a vertx url,when I switched from one page to another, the vertx server would always generate a new session id, so I lost session data set by previous page.

But,when I use iphone webview or PC Chrome to call the same vertx server, the session can be remembered correctly. so the error is only subject to android webview


### Do you have a reproducer?

we can reproducer the error following the steps below.


### Steps to reproduce


1. write a smiple verticle

publicclassTest1VerticleextendsAbstractVerticle{Routerrouter1;@Overridepublicvoidstart()throwsException{router1=Router.router(vertx);router1.route().handler(CookieHandler.create());router1.route().handler(SessionHandler.create(LocalSessionStore.create(vertx)));router1.route("/h6/*").handler(StaticHandler.create("web/h6"));router1.route("/hit").handler(this::hit);vertx.createHttpServer().requestHandler(router1::accept).listen(8080);}privatevoidhit(RoutingContextroutingContext){Sessionsession=routingContext.session();Integercnt=session.get("hitcount");cnt=(cnt==null?0:cnt)+1;session.put("hitcount",cnt);routingContext.response().putHeader("content-type","application/json;charset=UTF-8").end(newJsonObject().put("data","cnt="+cnt));}}

2. place 2 html files in the web/h6 file folder,named test3.html and test4.html respectively. test3.html source code:

<html><head><metacharset="utf-8"><metaname="viewport"content="width=device-width,initial-scale=1,minimum-scale=1,maximum-scale=1,user-scalable=no"/><title>test3.html</title><scripttype="text/javascript"src="//cdn.bootcss.com/jquery/2.0.3/jquery.min.js"></script></head><body><divid="myData"></div><divid="myData2"><ahref="test4.html"target="_blank">calltest4</a></div><scripttype="text/javascript"charset="utf-8">$.ajax({url:"/hit?time="+(newDate().getTime()),type:"post",dataType:"json",success:function(resp){console.log(resp)$("#myData").html(resp.data);},error:function(){$j("#myData").html("error.");me.resetload();}});</script></body></html>

the source code of test4.html is similar to the above,just replace the href to test3.html

3. ...

start the vertx verticle, and open an android browser,input the url (http://192.168.0.13:8080/h6/test3.html) in the browser,then submit

4. you can find ,after jump to the other html,the hit count remains to 1, but if you call the url in iphone or PC browser, the hit count will be found to increment correctly.

5,if we remove the target="_blank" in the html file, the session will work properly


2018-04-21 13:42 update:

I tested on several android phone ,and foud that the session problem did not appear on all android phone, Mi and Huawei could reproduce this error,but sumsung and Lenovo worked correctly.

at last,I added some code in my verticle file to address this problem:

//tomakesessionworkcorrectlyonHuaweiphone,setCookiePathtoroot'/'Set<Cookie>ccList=routingContext.cookies();for(Cookieck:ccList){ck.setPath("/");}