Variant play and documentation.

  There are few ways to play the game I'm implementing.  For example, one or
  two cards can be drawn at a time, the discard pile can be reshuffled or not,
  and such like. Can I choose which of these rules I prefer to implement?

Yes, or you can support them all and let the player choose.  Make sure your
remember your design decisions so you can document them.

  I was wondering if you could give us a brief example of the sort of
  javadoc you're looking for our code to include.

I was going to, then thought it might be better to let you muddle through the
documentation on your own.  The documentation you submit will be your first
draft, and you'll have the opportunity to rework it in a later submission.  For
now, just keep in mind the criteria:  somebody else should be able to play the
game (that is, write a front end) from just reading your documentation alone
(that is, without following links external to your documentation).

If you have questions about the mechanics of javadoc itself, the notes you took
when you read the Documentation Comments section of Chapter 4 should be able to
answer them.  Basic javadoc will be fine; you don't have to do anything wizzy
unless you want to.