Dart APIunself_local_databaseCollectionDataextra extra property Null safety String extra final Implementation final String extra; unself_local_database unself_local_database CollectionData extra property CollectionData class Constructors CollectionData fromJson Properties created createRule deleteRule extra hashCode id listRule name runtimeType system type updated updateRule viewRule Methods copyWith noSuchMethod toColumns toCompanion toJson toJsonString toString Operators operator ==