I'm just missing some error message in the Test Cases, would be nice knowing what the input was that I failed on.

Thanks, I fixed with your review

• Test methods can be package-private and reference solution should be private.
• Please correct the indentation of the third fixed/sample test.

Thanks for the review, I already edit this version with your observations.

Rejecting as superseded by https://www.codewars.com/kumite/643681a1b6eeb201fbfa2609?sel=6465e68605eaef004b4b83dd

Rejecting as superseded by https://www.codewars.com/kumite/643681a1b6eeb201fbfa2609?sel=6465e68605eaef004b4b83dd

Rejecting as superseded by https://www.codewars.com/kumite/643681a1b6eeb201fbfa2609?sel=6465e68605eaef004b4b83dd

Rejecting as superseded by https://www.codewars.com/kumite/643681a1b6eeb201fbfa2609?sel=6465e68605eaef004b4b83dd

• First of all, you do not have to fork every time to make some changes. You can edit if the fork is not approved, rejected, or deprecated.

Issues:

• @Tag annotation is not the one which sohuld be used hee, it serves different purpose. I think what you are looking for is @DisplayName?
• Tests should not System.out.println. If you want to present inputs (which is very good thing to do), it's better to use custom assertion messages, or test titles.
• Is empty array a valid input for this kata? If yes, there should be a fixed test with an empty array.
• Reference solution function (convert) should be private, or even better, a local lambda accessible only in randomTests()
• Stack is not used anymore, but it's still imported. The import can be removed.

Suggestions/code style:

• I think the boxing in for (Integer number: numbers) is unnecessary? Wouldn;t the for (int number: numbers) suffice?
• Recreating new Random() on every iteration is a waste. Just create one instance before the loop and use it.
• You can use random.ints(lo, hi).take(len).toArray() to generate an array of random ints, instead of looping explicitly.
• TODO note in submission tests is unnecessary.

Stack<T> should not be used in this case anyway and Deque<T> is preferred.

It's Java not JavaScript. You got java.util.Random, no need for
(int) Math.floor(Math.random() * (10 - 1 + 1) + 1)
when you can call nextInt(1,10) on a Random.

Isn't (10 - 1 + 1) just 10?

And please handle your raw types, new Stack() should be new Stack<>() f.ex

Java translation here.