getAttributes().put("Manifest-Version", "1.0");
    }

    @Override
    public String getContentCharset() {
        return contentCharset;
    }

    @Override
    public void setContentCharset(String contentCharset) {
        if (contentCharset == null) {
            throw new InvalidUserDataException("contentCharset must not be null");
        }
        if (!Charset.isSupported(contentCharset)) {