private Builder() {}

    /**
     * Sets the safe range of characters for the escaper. Characters in this range that have no
     * explicit replacement are considered 'safe' and remain unescaped in the output. If {@code
     * safeMax < safeMin} then the safe range is empty.
     *
     * @param safeMin the lowest 'safe' character
     * @param safeMax the highest 'safe' character