public static Integer getContentLengthIfPresent(ZuulMessage msg) {
        String contentLengthValue =
                msg.getHeaders().getFirst(com.netflix.zuul.message.http.HttpHeaderNames.CONTENT_LENGTH);
        if (!Strings.isNullOrEmpty(contentLengthValue)) {
            try {
                return Integer.valueOf(contentLengthValue);
            } catch (NumberFormatException e) {
                LOG.info("Invalid Content-Length header value on request. " + "value = {}", contentLengthValue, e);
            }
        }
        return null;
    }
Ensure decoded new lines are not propagated in headers, in order to prevent XSS

@param input - decoded header string
@return - clean header string
zuul-core/src/main/java/com/netflix/zuul/util/HttpUtils.java