@Override public EnumSet<Direction> getDirectionsByPosition(Position position) {
    EnumSet<Direction> directions = EnumSet.complementOf(
        EnumSet.of(Direction.NORTH, Direction.SOUTH));

    if (position.isFirstRow()) {
      directions.add(Direction.NORTH);
    }
    if (position.isLastRow()) {
      directions.add(Direction.SOUTH);
    }

    return directions;
  }
Selector that applies to all the items in a single column grouping them as a single item.
dividers/src/main/java/com/karumi/dividers/selector/ColumnGroupSelector.java