ZK fails when trying to build a navbar with includes such as:
<zk>
<navbar orient="vertical">
<include src="/WEB-INF/include/repository/repositories-nav.zul"/>
<include src="/WEB-INF/include/repository/users-nav.zul"/>
</navbar>
</zk>
Error is: org.zkoss.zk.ui.UiException: Unsupported child for navbar: <Include null>