Refactoring Conway's Game of Life in Java

I've recently revisited the Java version of Conway's Game of Life that I did nearly a year ago, to refactor it using some of the ideas I used in my more recent Clojure version.

This is the UML for the refactored design:

I eliminated the LivingCells class that appeared in the previous design.

I pushed a lot of code from the GameOfLife class into Generation to eliminate a bit of feature envy. This is GameOfLife's code now:

and this is Generation's one:

I also refactored the tests eliminating all the checks based on strings and using constructors with variadic parameters.

Following the idea in the Clojure version I managed to simplify the Rules interface a lot:

Most of the other changes are just renaming of methods, variables and parameters.

This new code keeps the functionality and characteristics of the previous version but it's much simpler.