> > It would have that throw an exception, a simple and clear IllegalStateException.

> that was my first thought as well. I think we discussed this once.

My take is as followed:

* your arguments make sense for a spec (be very clear and safe), it usually makes sense for a often used API, but I have to admit it's only a nice to have for a quasi private API
* why complicate the code with some exceptional case? Is the user likely to be tripped, very unlikely.

That's why I left it undefined in the first place. If you guys prefer it to be clearer at the expense of complicating the code, I won't argue.