docs: public static ColumnIO getArrayElementColumn(ColumnIO columnIO)
      {
          while (columnIO instanceof GroupColumnIO && !columnIO.getType().isRepetition(REPEATED)) {
              columnIO = ((GroupColumnIO) columnIO).getChild(0);
          }
  
          /* If array has a standard 3-level structure with middle level repeated group with a single field:
           *  optional group my_list (LIST) {
           *     repeated group element {
           *        required binary str (UTF8);
           *     };
           *  }
           */
          if (columnIO instanceof GroupColumnIO &&
                  columnIO.getType().getOriginalType() == null &&
                  ((GroupColumnIO) columnIO).getChildrenCount() == 1 &&
                  !columnIO.getName().equals("array") &&
                  !columnIO.getName().equals(columnIO.getParent().getName() + "_tuple")) {
              return ((GroupColumnIO) columnIO).getChild(0);
          }
  
          /* Backward-compatibility support for 2-level arrays where a repeated field is not a group:
           *   optional group my_list (LIST) {
           *      repeated int32 element;
           *   }
           */
          return columnIO;
      }