Dart APIunself_modelActivityarchiveId archiveId property Null safety String archiveId inherited Implementation String get archiveId => throw _privateConstructorUsedError; unself_model unself_model Activity archiveId property Activity class Constructors Activity fromJson Properties accountId appId archiveId copyWith created extra hashCode id labels name runtimeType source sourceId targetId timestamp type updated Methods noSuchMethod toJson toString Operators operator ==