org.zkoss.web.servlet.http.URLEncoder
From Documentation
Property: org.zkoss.web.servlet.http.URLEncoder
Default: javax.servlet.http.HttpServletResponse.encodeURL
[Since 5.0.0]
It specifies the class used to encode URL by including the session ID and the Servlet's context path, if necessary. The specified class must implement the Encodes.URLEncoder interface.
If the clients are far away from the server, you might override this class by encoding the URL of JavaScript and CSS files with a server nearby. Thus, it could shorten the time to load a page. For more information, please refer to Performance Tips.
In a sophisticated environment, e.g., Reverse Proxy, the encoded URL might have to be prefixed with some special prefix. To do that, you can implement the Encodes.URLEncoder interface, and then specify the class with this library property.