@Nullable
    private static CharSequence unwrapValue(CharSequence cs) {
        final int len = cs.length();
        if (len > 0 && cs.charAt(0) == '"') {
            if (len >= 2 && cs.charAt(len - 1) == '"') {
                // properly balanced
                return len == 2 ? "" : cs.subSequence(1, len - 1);
            } else {
                return null;
            }
        }
        return cs;
    }
Strips out the trailing 2-char separator from the specified {@link StringBuilder}.

@param buf a buffer where some cookies were encoded.
@return the {@link String} without the trailing separator
core/src/main/java/com/linecorp/armeria/common/CookieUtil.java