public SortedSet<EffectiveMeta> asSet() {
        return Collections.unmodifiableSortedSet(
                stream().collect(Collectors.toCollection(EffectiveMetaSet::createTreeSet)));
    }
@return An unmodifiable set of {@link EffectiveMeta} in ascending order
of {@link EffectiveMeta#getEffectiveMs()}
stroom-meta/stroom-meta-api/src/main/java/stroom/meta/api/EffectiveMetaSet.java