ExperimentApiResponse.fromJson constructor
Implementation
factory ExperimentApiResponse.fromJson(Map<String, dynamic> json) {
  var experimentsList = (json['experiments'] as List)
      .map((exp) => UserExperimentVariant.fromJson(exp))
      .toList();
  return ExperimentApiResponse(
    userType: json['userType'],
    experiments: experimentsList,
  );
}