private static void unicodeEscape(char c, StringBuffer buf) {
            final String chars = "0123456789abcdef";
            buf.append("\\u");
            buf.append(chars.charAt(15 & (c>>12)));
            buf.append(chars.charAt(15 & (c>>8)));
            buf.append(chars.charAt(15 & (c>>4)));
            buf.append(chars.charAt(15 & (c>>0)));
        }