@Override
                    protected EffectiveMetaSet create(final EffectiveStreamKey key) {
                        return streamSetAll.stream()
                                .collect(EffectiveMetaSet.collector(DUMMY_FEED, DUMMY_TYPE));
                    }
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