configure method
Implementation
@override
void configure(
    Axis<num> axis, ChartContext context, GraphicsFactory graphicsFactory) {
  super.configure(axis, context, graphicsFactory);
  if (axis is NumericAxis && viewport != null) {
    axis.setScaleViewport(viewport!);
  }
  if (axis is BucketingNumericAxis && threshold != null) {
    axis.threshold = threshold!;
  }
  if (axis is BucketingNumericAxis) {
    axis.showBucket = showBucket;
  }
}