docs: private DBIDs computeBadMedoids(ArrayDBIDs m_current, ArrayList<PROCLUSCluster> clusters, int threshold) {
      ModifiableDBIDs badMedoids = DBIDUtil.newHashSet(m_current.size());
      int i = 0;
      for(DBIDIter it = m_current.iter(); it.valid(); it.advance(), i++) {
        PROCLUSCluster c_i = clusters.get(i);
        if(c_i == null || c_i.objectIDs.size() < threshold) {
          badMedoids.add(it);
        }
      }
      return badMedoids;
    }