children property
Child columns. When non-empty this column becomes a header-only group (antd/naive-style column grouping): its label spans all descendant columns in a merged header row, and body cells are rendered only for the (recursively) leaf columns beneath it.
Groups are display-only — sorting/resizing/filtering/pinning are ignored on a group and apply only to its leaves. Only top-level columns may be pinned (SummerColumnPin); a column nested inside a group is always treated as part of the horizontally-scrollable middle band.
Implementation
final List<SummerDataColumn> children;