I'm seeing Integer.reverse behaviour change in recent JDK 20 EA builds, I think the culprit is JDK-8290034.

$ java -fullversion
openjdk full version "20-ea+12-790"

$ java -cp ~/ T
Exception in thread "main" java.lang.AssertionError: expected Integer.reverse(1) to be -2147483648, but was 128 after 307906 iterations
        at T.main(T.java:9)

class T {
  public static void main(String[] args) {
    long c = 0;
    int expected = -2147483648;
    while (true) {
      long r = Integer.reverse(1);
      if (r != expected) {
        throw new AssertionError(
            String.format(
                "expected Integer.reverse(1) to be %d, but was %d after %d iterations",
                expected, r, c));
      }
      c++;
    }
  }
}