@Override
        public String toString() {
            return "TimedResult{" +
                    "duration=" + duration +
                    ", cumulativeDuration=" + cumulativeDuration +
                    ", result=" + result +
                    '}';
        }
Measures the time taken to perform resultSupplier if isTimed is true.
If isTimed is false returns a {@link TimedResult} containing a zero duration.
stroom-util/src/main/java/stroom/util/logging/DurationTimer.java