areaColor

areaColor returns the color of the area for a given data value.
If not available, then the group color will use 10% opacity by default.

This property is for charts with line type. To activate a custom areaColor, in ConfigRenderLine there is includeArea which must be made true.

Type	Default
Color? Function(OrdinalGroup, OrdinalData, int?)?	null

configRenderLine: ConfigRenderLine(
    includeArea: true,
),
areaColor: (group, ordinalData, index) {
    return Colors.green.withOpacity(0.3);
},