The org.zkoss.zk.ui.util.SessionInit interface
A listener could implement SessionInit to initialize a session that is being created.
When ZK Loader is going to create a session, it invokes the
init method of this interface such that developers could plug the application-specific codes to initialize a session when it is created.
Instantiation: An independent instance of the given class is instantiated each time before the method is invoked. It means it is thread safe, and all information stored in non-static members will be lost after called.