...as opposed to just checking against "Java 6" and "Java 8."

I somewhat doubt that we'd get much out of this (and it might even have drawbacks if it starts flagging types like Unsafe?), but I wanted to record somewhere that I learned of this possibility.

I saw it in action in https://github.com/googleapis/google-http-java-client/blob/e957229fd77c08b7dd6233e2a243f6c675ba32bf/pom.xml#L515-L527