palindrome: product of two 3-digit numbers (java)

import java.util.stream.IntStream;

class Scratch {
  public static void main(String[] args) {


    int lowerBound = 100;
    int upperBound = 999;

    System.out.println(
        IntStream.range(lowerBound, upperBound).flatMap(x ->
            IntStream.range(lowerBound, upperBound).map(y -> x * y)
                .filter(Scratch::isPalindrome)
        ).max().getAsInt());
  }

  private static boolean isPalindrome(int i) {
    String forward = Integer.toString(i);
    String reverse = new StringBuilder(Integer.toString(i)).reverse().toString(); // yuk
    return forward.equals(reverse);
  }
}