@Override
    public RefDataValueProxy getValueProxy(final MapDefinition mapDefinition, final String key) {
        return getEffectiveStore(mapDefinition).getValueProxy(mapDefinition, key);
    }
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