code: private static int compareUnsigned(int left, int right) {
      // NOTE: JDK 7 does not have a built-in operation for this, other than casting to longs.
      //       In JDK 8 it's just Integer.compareUnsigned(left, right).  For now we emulate it
      //       by shifting the sign bit away, with a fallback second compare only if needed.
      int diff = (left >>> 2) - (right >>> 2);
      return diff != 0 ? diff : (left & 3) - (right & 3);
    }
docs: Compare two unsigned integers.