private boolean shouldRoll(final Instant currentTime) {
        return (oldestAllowed != null && currentTime.isAfter(oldestAllowed)) ||
                output.getCurrentOutputSize() > rollSize;
    }
Try to flush this destination if it needs to and roll it if it needs to.
If this destination is rolled then this method will return true.

@return True if this destination has been rolled.
stroom-pipeline/src/main/java/stroom/pipeline/destination/RollingDestination.java