public long calculateTimeBetweenButIfNoEndThenUseNow(StartAndEnd sae) {
        if (sae.startNotFound()) {
            return 0;
        }

        // If no end state found, then default to now.
        if (sae.endNotFound()) {
            sae.endTime = now();
        }

        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