GridPadCells.kt

public data class GridPadCells(   
    val rowSizes: ImmutableList<GridPadCellSize>,   
    val columnSizes: ImmutableList<GridPadCellSize>
) {

    public constructor(
        rowSizes: Iterable<GridPadCellSize>, columnSizes: Iterable<GridPadCellSize>
    ) : this(rowSizes = rowSizes.toImmutableList(), columnSizes = columnSizes.toImmutableList())
    
    //...
  
    public class Builder(rowCount: Int, columnCount: Int) {

        private val rowSizes: MutableList<GridPadCellSize> = GridPadCellSize.weight(rowCount)
        private val columnSizes: MutableList<GridPadCellSize> = GridPadCellSize.weight(columnCount)

        public fun rowSize(index: Int, size: GridPadCellSize): Builder = apply {
            rowSizes[index] = size
        }

        public fun columnSize(index: Int, size: GridPadCellSize): Builder = apply {
            columnSizes[index] = size
        }

        public fun build(): GridPadCells {
            return GridPadCells(
                rowSizes = rowSizes, columnSizes = columnSizes
            )
        }
    }
}