private void setDbMaxSizeProperty(final ByteSize size) {
        referenceDataConfig = referenceDataConfig.withLmdbConfig(referenceDataConfig.getLmdbConfig()
                .withMaxStoreSize(size));
    }
Make sure that it copes with a map not being in an early stream but is in a later one.
stroom-app/src/test/java/stroom/pipeline/refdata/TestReferenceData.java