code: @Override
      public Iterable<? extends GeoDocument> findAllDocuments() {
          final SortedSet<String> names = new TreeSet<>();
          names.addAll(map.keySet());
          final List<GeoDocument> list = new ArrayList<>();
          for (final String name : names) {
              list.add(getDocument(name));
          }
          return list;
      }
docs: {@inheritDoc}