The ViewNumberRetrievedEvent class represents an event that
should be fired whenever a view number is retrieved. A view number is always
associated with an ICEfaces ID.
Constructs a ViewNumberRetrievedEvent with the specified
source and viewNumber.
Parameters: source - the HTTP session. Parameters: iceFacesId - the ICEfaces ID identifying the session. Parameters: viewNumber - the view number that has been retrieved. throws: IllegalArgumentException - if the one of the following happens: