code: public ArrayList<PartialPieceInfo> getDownloadQueue() {
          partial_piece_info_vector v = new partial_piece_info_vector();
          th.get_download_queue(v);
          int size = (int) v.size();
          ArrayList<PartialPieceInfo> l = new ArrayList<>(size);
  
          for (int i = 0; i < size; i++) {
              l.add(new PartialPieceInfo(v.get(i)));
          }
  
          return l;
      }
docs: Returns an array (list) with information about pieces that are partially
  downloaded or not downloaded at all but partially requested. See
  {@link PartialPieceInfo} for the fields in the returned vector.
  
  @return a list with partial piece info