In my opinon, the former syntax is easier to read. I've never found stacking keywords to be a very clear way of annotating types (see C's `unsigned long long`, where the second `long` is a shorthand for `long int`). The whole "private final static" chain already detracts from readability, in my opinion.

I find the question mark to be quite clear ("its a string, but is it? Could be nothing!"), and I find the exclamation mark to be a clear opposite of the question mark.

This annotation is also very common in other languages. I don't think it makes sense for Java to invent its own notation here.