copyWith method
Создает экземпляр с заданными параметрами
Implementation
@override
Member copyWith({
String? memberId,
String? memberName,
bool? isPayee,
}) {
return Member(
memberId: memberId ?? this.memberId,
memberName: memberName ?? this.memberName,
isPayee: isPayee ?? this.isPayee,
);
}