class SimpleCatalogUtilsService implements CatalogUtilsService {

    @Override
    public Difference getCommitDifference(List<Resource> commits, RepositoryConnection conn) {
        Map<Statement, Integer> additions = new HashMap<>();
        Map<Statement, Integer> deletions = new HashMap<>();
        commits.forEach(commitId -> aggregateDifferences(additions, deletions, commitId, conn));

        return new Difference.Builder()
                .additions(mf.createModel(additions.keySet()))
                .deletions(mf.createModel(deletions.keySet()))
                .build();
    }

}