toOptionsJSON method 
    
    
    
  Implementation
  @override
void toOptionsJSON(StringBuffer buffer) {
  super.toOptionsJSON(buffer);
  if (animation != null) {
    buffer.writeAll(['"animation":', animation?.toJSON(), ','], '');
  }
  if (borderColor != null) {
    buffer.writeAll(['"borderColor":', jsonEncode(borderColor), ','], '');
  }
  if (brightness != null) {
    buffer.writeAll(['"brightness":', brightness, ','], '');
  }
  if (color != null) {
    buffer.writeAll(['"color":', jsonEncode(color), ','], '');
  }
  if (enabled != null) {
    buffer.writeAll(['"enabled":', enabled, ','], '');
  }
  if (lineWidthPlus != null) {
    buffer.writeAll(['"lineWidthPlus":', lineWidthPlus, ','], '');
  }
}