[peeters]

>>Except these aren't at all the same. With a reference, you have no good way of telling whether your reference IS nullable.

>As the article mentions, we have annotations to do just that.

Your mileage may vary, but my experience with nullable/nonnull annotations is that because they are not used across the board, you are either left with a ton of false positives or a ton of false negatives. The fact that there hasn't really been a great standardization in the core language is probably evidence of that (yes, JSR305 exists, but the JDK doesn't enforce its constraints by default).

With Optional, it's a clean slate. You can simply say "a reference to an Optional shall never be null" and you could probably enable such an enforcement for an existing project. Of course it's not going to be 100% while it's still a normal reference type, but catching 99% of the cases is a really big improvement!