Spurious intersection when testing circle approximation

[jbellis]

Hi Stanislav, thanks for publishing this library!

I found a bug where the endpoints of adjacent segments of a polygon are flagged as intersecting, and I've created a test case over here: jbellis@7b01c75

(I also had to make some modifications to get it to build with Java 16 and 17, these are committed in the history, I'm happy to send a pull request or you can just cherry-pick them.)