Index of the first column an aggregate row's label can land on (see resolveAggregateRow) —
-1 if every column has an aggregate, meaning the label gets omitted entirely. Exposed so the
render layer can merge that slot with any immediately-following empty columns into one wider
display cell (colSpan), without needing resolveAggregateRow to also return this index.
Index of the first column an aggregate row's label can land on (see resolveAggregateRow) — -1 if every column has an aggregate, meaning the label gets omitted entirely. Exposed so the render layer can merge that slot with any immediately-following empty columns into one wider display cell (colSpan), without needing resolveAggregateRow to also return this index.