createRenderer method
Create the range column series renderer.
Implementation
@override
RangeColumnSeriesRenderer<T, D> createRenderer() {
  RangeColumnSeriesRenderer<T, D> seriesRenderer;
  if (onCreateRenderer != null) {
    seriesRenderer =
        onCreateRenderer!(this) as RangeColumnSeriesRenderer<T, D>;
    return seriesRenderer;
  }
  return RangeColumnSeriesRenderer<T, D>();
}