<zk>
<a href="http://test?a=1&b=2">TEST HYPERLINK</a>
</zk>

When I test above zul, console will show

嚴重的: Servlet.service() for servlet zkLoader threw exception
org.zkoss.lang.SystemException: org.xml.sax.SAXParseException: The reference to entity "requestUrl" must end with the ';' delimiter.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at org.zkoss.lang.Classes.newInstance(Classes.java:73)
at org.zkoss.lang.Exceptions.wrap(Exceptions.java:161)
at org.zkoss.lang.SystemException$Aide.wrap(SystemException.java:42)
at org.zkoss.util.resource.ResourceCache.get(ResourceCache.java:157)
at org.zkoss.web.util.resource.ResourceCaches.get(ResourceCaches.java:120)
at org.zkoss.zk.ui.metainfo.PageDefinitions.getPageDefinition(PageDefinitions.java:140)
at org.zkoss.zk.ui.impl.AbstractUiFactory.getPageDefinition(AbstractUiFactory.java:158)
at org.zkoss.zk.ui.http.DHtmlLayoutServlet.process(DHtmlLayoutServlet.java:208)
at org.zkoss.zk.ui.http.DHtmlLayoutServlet.doGet(DHtmlLayoutServlet.java:135)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:602)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Unknown Source)