@MatchMedia: NPE in BinderImpl if cookies are null

problem description

Reproducible on first load when client has no cookies.

steps to reproduce

1. clear all cookies with chrome developer tool
2. load the 3338.zul

current result

NullPointerException - cookies can be null.

2016-09-23 09:37:45.388:WARN::/uipattern/3338.zul
java.lang.NullPointerException
at org.zkoss.bind.impl.BinderImpl.init(BinderImpl.java:354)
at org.zkoss.bind.AnnotateBinder.init(AnnotateBinder.java:58)
at org.zkoss.bind.BindComposer.doBeforeComposeChildren(BindComposer.java:164)
at org.zkoss.zk.ui.impl.UiEngineImpl.doBeforeComposeChildren(UiEngineImpl.java:997)
at org.zkoss.zk.ui.impl.UiEngineImpl.execCreateChild0(UiEngineImpl.java:937)
at org.zkoss.zk.ui.impl.UiEngineImpl.execCreateChild(UiEngineImpl.java:895)
at org.zkoss.zk.ui.impl.UiEngineImpl.execCreate0(UiEngineImpl.java:777)
at org.zkoss.zk.ui.impl.UiEngineImpl.execCreateChild(UiEngineImpl.java:841)
at org.zkoss.zk.ui.impl.UiEngineImpl.execCreate0(UiEngineImpl.java:797)
at org.zkoss.zk.ui.impl.UiEngineImpl.execCreate(UiEngineImpl.java:740)
at org.zkoss.zk.ui.impl.UiEngineImpl.execNewPage0(UiEngineImpl.java:460)
at org.zkoss.zk.ui.impl.UiEngineImpl.execNewPage(UiEngineImpl.java:369)
at org.zkoss.zk.ui.http.DHtmlLayoutServlet.process(DHtmlLayoutServlet.java:211)
at org.zkoss.zk.ui.http.DHtmlLayoutServlet.doGet(DHtmlLayoutServlet.java:137)

expected result

no exception.

root cause

https://github.com/zkoss/zk/blob/master/zkbind/src/org/zkoss/bind/impl/BinderImpl.java

Line 354:
for (Cookie c : cookies) {

debug info

• reproduced it with jetty 6 (jetty 7 or 8 returns Cookie[0] so don't cause this error)
• according to javadoc of getCookies(), https://tomcat.apache.org/tomcat-5.5-doc/servletapi/javax/servlet/http/HttpServletRequest.html#getCookies(), it could return null.
• Tomcat 6, 7, 8 also has this issue