docs: public static <V extends SpatialComparable> String getColumnLabel(Relation<? extends V> rel, int col) {
      SimpleTypeInformation<? extends V> type = rel.getDataTypeInformation();
      if(!(type instanceof VectorFieldTypeInformation)) {
        return "Column " + col;
      }
      final VectorFieldTypeInformation<?> vtype = (VectorFieldTypeInformation<?>) type;
      String lbl = vtype.getLabel(col);
      return (lbl != null) ? lbl : ("Column " + col);
    }