FitNesse is started in the set up fixture so it's running,
FitNesse Status
isRunning?
true

A Graceful shutdown is initiated by making an HTTP request with the responder=shutdown
Response Requester.
uri valid?
?responder=shutdown true

Wait a bit for things to settle down
Sleep 100

Now FitNesse is no longer running.
FitNesse Status
isRunning?
false