public long calculateTimeBetween(StartAndEnd sae) {
        if (sae.startNotFound() || sae.endNotFound()) {
            return 0;
        }
        return sae.endTime - sae.startTime;
    }
NOTE: This is NOT nanos since epoch. It's just since an arbitrary point in time. So only use relatively.
zuul-core/src/main/java/com/netflix/zuul/passport/CurrentPassport.java