static RequestDuration of(Duration duration) {
        return new RequestDuration().complete(duration.toNanos());
    }
Contains start and end time. Exposes a duration, and lets you measure the time difference between 2 requests.
It does use System.nanoTime to get a steady clock.

@author baldersheim
container-search/src/main/java/com/yahoo/search/dispatch/RequestDuration.java