private Map<String, Integer> getCachedFieldPositions() {
        if (cachedFieldPositions == null) {
            // sort the list of fields as this will help us later when generating StatisticEvents.
            sortFieldListAndCachePositions();
        }
        return cachedFieldPositions;
    }
Cache the positions of the fields.
stroom-core-shared/src/main/java/stroom/statistics/impl/hbase/shared/StroomStatsStoreEntityData.java