class RdfEngine implements Engine {

    @Override
    public void deleteGroup(String groupTitle) {
        try (RepositoryConnection conn = repository.getConnection()) {
            Optional<Resource> optId = getGroupId(groupTitle, conn);
            if (!optId.isPresent()) {
                throw new IllegalArgumentException("Group with that id does not exist");
            }
            conn.remove(optId.get(), null, null, context);
        }
    }

}