code: public Set<HBeanRow> filterUnvisted(Set<HBeanRow> rows) {
          Set<HBeanRow> unvisted = new HashSet<>();
          for (HBeanRow row : rows) {
              if (!references.containsKey(row) && !inital.containsKey(row)) {
                  unvisted.add(row);
              }
          }
          return unvisted;
      }
docs: Filter out the rows that we have not yet visited.