class HttpUtil {

    public static long getContentLength(HttpMessage message) {
        String value = message.headers().get(HttpHeaderNames.CONTENT_LENGTH);
        if (value != null) {
            return Long.parseLong(value);
        }

        // We know the content length if it's a Web Socket message even if
        // Content-Length header is missing.
        long webSocketContentLength = getWebSocketContentLength(message);
        if (webSocketContentLength >= 0) {
            return webSocketContentLength;
        }

        // Otherwise we don't.
        throw new NumberFormatException("header not found: " + HttpHeaderNames.CONTENT_LENGTH);
    }

    private  HttpUtil();

}