@Override
    public int hashCode() {

        return Objects.hash(createTimeEpochMs, effectiveTimeEpochMs, processingState);
    }
@return The time an entry for the associated ref stream definition was accessed,
truncated to the nearest PROCESSING_INFO_TRUNCATION_UNIT.
stroom-pipeline/src/main/java/stroom/pipeline/refdata/store/RefDataProcessingInfo.java