I don't think so, that is good practice to write as short as possible, but it's fun;

Duplicate of existed kata...

No properly set-up (have to copy array definition from instruction)

My feedback: https://www.codewars.com/kata/the-impossible-kata/java

Was here...

Maybe when one argument is null, and another is set - return another?

Left side is always bigger than right side?

I think, that should raise exception when name is too short, no "Error: Name too short"

If somebody will use that method, and trust us that it returns nickname, and for example gives the name Ula he gots "Error: Name too short"
Nobody wants that nickname :D

That Kata learning bad practices (public variables)

I think, that is too basic