class IncrementalRelativeFileSets {

    @NonNull
    public static ImmutableMap<RelativeFile, FileStatus> union(
            @NonNull Iterable<ImmutableMap<RelativeFile, FileStatus>> sets) {
        Map<RelativeFile, FileStatus> map = Maps.newHashMap();
        for (ImmutableMap<RelativeFile, FileStatus> set : sets) {
            map.putAll(set);
        }

        return ImmutableMap.copyOf(map);
    }

    private  IncrementalRelativeFileSets();

}