BigDecimal two = BigDecimal.valueOf(2); // Android doesn't have BigDecimal.TWO yet
    BigDecimal bigMean = new BigDecimal(bigX.add(bigY)).divide(two, RoundingMode.FLOOR);
    return bigMean.intValueExact();
  }

  private static boolean fitsInInt(BigInteger big) {
    return big.bitLength() <= 31;
  }

  @J2ktIncompatible
  @GwtIncompatible // NullPointerTester
  public void testNullPointers() {