public static StroomDuration duration(final StroomDuration stroomDuration) {
        return stroomDuration != null
                ? stroomDuration
                : StroomDuration.ZERO;
    }
Returns the passed stroomDuration if it is non-null else returns a ZERO {@link StroomDuration}
stroom-util/src/main/java/stroom/util/NullSafeExtra.java