org.zkoss.zk.WPD.cache
From Documentation
Property:
org.zkoss.zk.WPD.cache
Applicable: globally in zk.xml via <library-property> not as <custom-attribute>
Default: true
Since 5.0.7
Specifies whether to cache the result of ZK WPD files (the JavaScript code for widgets) at the server. By default, it is enabled. It means the JavaScript code specified in a WPD file is loaded and cached at the server. The performance is good. However, if you are debugging the widget's client-side code and you'd like to modify the content without restarting the server, you could disable the caching of WPD files.
Notice that you don't have to turn it off if you restart the server each time you modify the widget's client-side code.