code: @Override
      public void printGroundtruth(final Long user, final PrintStream out, final OUTPUT_FORMAT format) {
          for (Long i : getTest().getUserItems(user)) {
              Double d = getTest().getUserItemPreference(user, i);
              if (d >= getThreshold()) {
                  final Map<Long, Double> tmp = new HashMap<Long, Double>();
                  tmp.put(i, d);
                  printGroundtruth(user + "_" + i, tmp, out, format);
              }
          }
      }
docs: {@inheritDoc}