the is_even package does not provide much worth indeed because it simply negates is_odd and thereby all its benefit.

It's dependency is_odd on the other hand provides at least some additional checks (it also checks if the value is a valid integer below the max int value)

And while I would indeed see uses for such methods (especially with the other checks, no simple oneliners) in some cases, especially in testing: This is stuff you write yourself, throw it in a e.g. NumberUtils class and everything is fine. You do never depend on an external library for that. The benefit (not spending a few seconds to write it) does not outweigh any of the drawbacks that come with external libraries.