public static DurationTimer startTimerIfDebugEnabled(final Logger logger) {
        return logger != null && logger.isDebugEnabled()
                ? DurationTimer.start()
                : null;
    }
If DEBUG logging is enabled, create, start and return a new {@link DurationTimer}
instance, else just return null.
This avoids unnecessary object creation if DEBUG is not enabled.
stroom-util/src/main/java/stroom/util/logging/LogUtil.java