Author here. Great callout. That's the -XX:+OmitStackTraceInFastThrow optimization, been around since JDK 5. The C2 compiler detects exceptions thrown repeatedly from the same site and starts reusing a preallocated instance without filling the stack trace. Good for performance, but it makes debugging harder in production since you lose the trace. You can disable it with -XX:-OmitStackTraceInFastThrow if you need the traces back.

ah, thank you. Haven't worked in java for a bit now, but that was the only one I read where I was like "I'm sure we didn't have to avoid this when I worked on java".

The rest were all very familiar. Well, apart from the new stuff. I think most of my code was running in java 6...