if ((a ^ b) < 0 | (a ^ naiveSum) >= 0) {
      // If a and b have different signs or a has the same sign as the result then there was no
      // overflow, return.
      return naiveSum;
    }
    // we did over/under flow, if the sign is negative we should return MAX otherwise MIN
    return Long.MAX_VALUE + ((naiveSum >>> (Long.SIZE - 1)) ^ 1);
  }

  /**

    BigInteger bigX = BigInteger.valueOf(x);
    BigInteger bigY = BigInteger.valueOf(y);
    BigDecimal bigMean =
        new BigDecimal(bigX.add(bigY)).divide(BigDecimal.valueOf(2), BigDecimal.ROUND_FLOOR);
    // parseInt blows up on overflow as opposed to intValue() which does not.
    return Integer.parseInt(bigMean.toString());
  }

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

     * determined experimentally to match our desired probability of false positives.
     */
    // NB: yes, this is surprisingly high, but that's what the experiments said was necessary
    // Raising this number slows the worst-case contains behavior, speeds up hashFloodingDetected,
    // and reduces the false-positive probability.
    static final int MAX_RUN_MULTIPLIER = 13;

    /**

    errorInput.set(0);

    runGetIdempotencyTest(errorComposedFuture, MyError.class);

    /*
     * Try again when the input's value is already filled in, since the flow is
     * slightly different in that case.
     */
    exceptionComposedFuture =
        transform(exceptionInput, newOneTimeExceptionThrower(), directExecutor());

    errorInput.set(0);

    runGetIdempotencyTest(errorComposedFuture, MyError.class);

    /*
     * Try again when the input's value is already filled in, since the flow is
     * slightly different in that case.
     */
    exceptionComposedFuture =
        transform(exceptionInput, newOneTimeExceptionThrower(), directExecutor());

    BigInteger bigX = BigInteger.valueOf(x);
    BigInteger bigY = BigInteger.valueOf(y);
    BigDecimal bigMean =
        new BigDecimal(bigX.add(bigY)).divide(BigDecimal.valueOf(2), BigDecimal.ROUND_FLOOR);
    // parseInt blows up on overflow as opposed to intValue() which does not.
    return Long.parseLong(bigMean.toString());
  }

  private static boolean fitsInLong(BigInteger big) {
    return big.bitLength() <= 63;
  }

    BigInteger bigX = BigInteger.valueOf(x);
    BigInteger bigY = BigInteger.valueOf(y);
    BigDecimal bigMean =
        new BigDecimal(bigX.add(bigY)).divide(BigDecimal.valueOf(2), BigDecimal.ROUND_FLOOR);
    // parseInt blows up on overflow as opposed to intValue() which does not.
    return Integer.parseInt(bigMean.toString());
  }

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

    BigInteger bigX = BigInteger.valueOf(x);
    BigInteger bigY = BigInteger.valueOf(y);
    BigDecimal bigMean =
        new BigDecimal(bigX.add(bigY)).divide(BigDecimal.valueOf(2), BigDecimal.ROUND_FLOOR);
    // parseInt blows up on overflow as opposed to intValue() which does not.
    return Long.parseLong(bigMean.toString());
  }

  private static boolean fitsInLong(BigInteger big) {
    return big.bitLength() <= 63;
  }