Disclaimer: I didn't even have a peek at the code yet. However...

Examples in the readme seem to imply that Java 8 is required, since lambdas are used.

But when referring to this:

https://github.com/goldmansachs/gs-collections/blob/master/pom.xml#L337

it looks like the only requirement is Java 5; what is more, the maven-compiler-plugin configuration does not specify a version.

So, what is what?