Hi Marzo,
The assignment you deliver must "
work under a production (not development) version of the Sun Microsystems' Java 2 platform and that platform must not have been superseded by a new production version for more than 18 months by the time you make your submission." (from the instructions)
So you can develop using any version of the JDK you like, and take as long as you like to do it, but when you do finally submit it,
you should check that your version of the JDK has not been superseded by more than 18 months, and if it has, just make sure it can be compiled and run in a later version of the JDK.
Regards, Andrew
P.S. Must get my bio updated. I was working in Shanghai for the last 6 months, but have just come back to Melbourne for a while.