It is, except you can omit the code for main and change the class name to match with the tests!

no

xDD

I have the same problem

It should in my opinion, im very angry at one part of my answer needing to be dumbed down not fit a worse requirement :(

Please use spoiler flag next time.

list size will always be at least 3 numbers

There are some problems with the Java translation.

I don't do Java.

Because nobody reviewed it, and there is no way this is a kata issue (= a bug in the kata).

how?

For incrementing sequences, 0 should come after 9, and not before 1, as in 7890

No.

I tried indices as well, but didn't work anyway

My guess is as good as yours (haven't solved the kata). But I think the sum of those indices is the answer.