@Override
    public void purgeOldData(final StroomDuration purgeAge) {
        LOGGER.debug("purgeOldData({}) called", purgeAge);
        // Purge sequentially
        getAllStoresAsStream()
                .forEach(refDataOffHeapStore -> {
                    LOGGER.debug("Calling purgeOldData({}) on store {}", purgeAge, refDataOffHeapStore);
                    refDataOffHeapStore.purgeOldData(purgeAge);
                });
        checkLegacyStoreState();
    }
Get all ref stores keyed by feed name

@return Map of feedName => {@link RefDataOffHeapStore}
stroom-pipeline/src/main/java/stroom/pipeline/refdata/store/offheapstore/DelegatingRefDataOffHeapStore.java