class SimpleCatalogUtilsService implements CatalogUtilsService {

    @Override
    public void updateCommit(Commit commit, Model additions, Model deletions, RepositoryConnection conn) {
        Resource resource = commit.getGenerated_resource().stream().findFirst()
                .orElseThrow(() -> new IllegalArgumentException("Commit does not have a Revision."));
        Revision revision = revisionFactory.getExisting(resource, commit.getModel())
                .orElseThrow(() -> new IllegalStateException("Could not retrieve expected Revision."));
        updateCommit(commit.getResource(), revision, additions, deletions, conn);
    }

}