org.zkoss.zk.ui.ShadowDefaultHost.class
From Documentation
Property:
org.zkoss.zk.ui.ShadowDefaultHost.class
Applicable: globally in zk.xml via <library-property> not as <custom-attribute>
Default: org.zkoss.zul.NoDOM (it implies Thread.currentThread().getContextClassLoader())
Since 8.0.3
It specifies the name of the class as the default host component of shadow elements. It would be generated when the host of shadow elements is null.