toJson method Null safety

Implementation

Map<String, dynamic> toJson() {
  final json = <String, dynamic>{};
  json.addAll({
    'kind': kind,
    'inclusiveTicks': inclusiveTicks,
    'exclusiveTicks': exclusiveTicks,
    'resolvedUrl': resolvedUrl,
    'function': function?.toJson(),
  });
  return json;
}