Rejected, this fork only removes the random tests & changes the solution class name

Rejected. This fork doesn't fix the biggest issue (missing random tests) while adding unnecessary input validation tests.

... words will always be separated by a space.

Rejected. Handling multiple spaces is out of the spec.

What's the goal of this fork? Why does it remove random tests?

Guys, what do you think about range of [Integer.MIN_VALUE, Integer.MAX_VALUE] ?

It is allowed by definition, but I'm not shure if it is possible to process in Java using int[] as resulting array,
because total of terms will overflow an int type

Maybe it is worth to mention more boundaries in description

Sometimes tests may fail
because of n provided as int and not as long
as if there was no L in value literal

like so

        assertArrayEquals(new int[] {7, 3, 8, 4, 2, 0, 8, 6, 8, 2}, NumToRev.digitize(2868024837));
        assertArrayEquals(new int[] {0, 2, 9, 3, 9, 8, 2, 6, 7, 5, 4}, NumToRev.digitize(45762893920));

instead of

        assertArrayEquals(new int[] {7, 3, 8, 4, 2, 0, 8, 6, 8, 2}, NumToRev.digitize(2868024837L));
        assertArrayEquals(new int[] {0, 2, 9, 3, 9, 8, 2, 6, 7, 5, 4}, NumToRev.digitize(45762893920L));

I must elaborate, you need to keep remaining characters unchanged.