Lukas' palindrome challenge solved using Vavr

SubstringPalindromes.java

Seq<Tuple<Integer, Integer>> getSubstringPalindromes(String s) {
    final N = s.length();
    return List.range(0, N-1)
        .flatMap(i -> List.of(Tuple.of(i, i+1), Tuple.of(i, i+2)))
        .flatMap(t -> List.unfold(t, tt -> {
            final int i = tt._1;
            final int j = tt._2;
            return i >= 0 && j <= N && isPalindrome(s.substring(i, j))
                ? Option.some(Tuple(i-1, j+1), tt)
                : Option.none();
        }));
}

boolean isPalindrome(String string) {
    final gnirts = new StringBuilder(string).reverse().toString(); 
    return string.equals(gnirts);
}