toOptionsJSON method

Implementation

@override
void toOptionsJSON(StringBuffer buffer) {
  super.toOptionsJSON(buffer);

  if (index != null) {
    buffer.writeAll(['"index":', index, ','], '');
  }
  if (periods != null) {
    buffer.write('"periods":[');
    for (var item in periods!) {
      buffer.writeAll([item, ','], '');
    }
    buffer.write('],');
  }
}