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.