toOptionsJSON method
Implementation
@override
void toOptionsJSON(StringBuffer buffer) {
super.toOptionsJSON(buffer);
if (negativeColor != null) {
buffer.writeAll(['"negativeColor":', jsonEncode(negativeColor), ','], '');
}
if (positiveColor != null) {
buffer.writeAll(['"positiveColor":', jsonEncode(positiveColor), ','], '');
}
}