What is the meaning of currentUser.name in the SWF Reference

I've seen the below on-start action from the swf reference..
Just notice the currentUser.name... where it came from? how to set the value?

Code:

---

        <on-start>
                <evaluate expression="bookingService.createBooking(hotelId, currentUser.name)"
                result="flowScope.booking" />
        </on-start>

---

anyone here, that may give me an idea... of currentUser.name?

currentUser is a special EL variable that gives access to the currently authenticated Principal.

http://static.springsource.org/sprin...l#el-variables

This is equivalent to HttpServletRequest.getUserPrincipal()

So currentUser.name will basically give you the name of the logged in user.