BarChartEvent
BarChartEvent class has the following values:
bar_index
 Bar's index or -1 if chart is hovered or clicked outside of any bar.
rod_index
 Rod's index or -1 if chart is hovered or clicked outside of any bar.
stack_item_index
 Stack item's index or -1 if chart is hovered or clicked outside of any bar.
type
 Event's type such as PointerHoverEvent, PointerExitEvent, etc.