private int buildHash(final long[] sortedMetaIds) {
        return Arrays.hashCode(sortedMetaIds);
    }
@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