main.dart

void main() {
  print(Foo(
    a1: 'a',
    a2: 'b',
    a3: 'b',
    a4: 'b',
    a5: 'b',
    a6: 'b',
    a7: 'b',
    a8: 'b',
    a9: 'b',
    a10: 'b',
    a11: 'b',
    a12: 'b',
    a13: 'b',
    a14: 'b',
    a15: 'b',
  ));
  print(Foo(
    a1: 'a',
    a2: 'b',
    a3: 'b',
    a4: 'b',
    a5: 'b',
    a6: 'b',
    a7: 'b',
    a8: 'b',
    a9: 'b',
    a10: 'b',
    a11: 'b',
    a12: 'b',
    a13: 'b',
    a14: 'b',
    a15: 'b',
  ).copyWith(
    a1: 'a',
    a2: 'b',
    a3: 'b',
    a4: 'b',
    a5: 'b',
    a6: 'b',
    a7: 'b',
    a8: 'b',
    a9: 'b',
    a10: 'b',
    a11: 'b',
    a12: 'b',
    a13: 'b',
    a14: 'b',
    a15: 'b',
  ));
}

class Foo {
  const Foo({
    required this.a1,
    required this.a2,
    required this.a3,
    required this.a4,
    required this.a5,
    required this.a6,
    required this.a7,
    required this.a8,
    required this.a9,
    required this.a10,
    required this.a11,
    required this.a12,
    required this.a13,
    required this.a14,
    required this.a15,
  });

  final String a1;
  final String a2;
  final String a3;
  final String a4;
  final String a5;
  final String a6;
  final String a7;
  final String a8;
  final String a9;
  final String a10;
  final String a11;
  final String a12;
  final String a13;
  final String a14;
  final String a15;

  Foo copyWith({
    String? a1,
    String? a2,
    String? a3,
    String? a4,
    String? a5,
    String? a6,
    String? a7,
    String? a8,
    String? a9,
    String? a10,
    String? a11,
    String? a12,
    String? a13,
    String? a14,
    String? a15,
  }) {
    return Foo(
      a1: a1 ?? this.a1,
      a2: a2 ?? this.a2,
      a3: a3 ?? this.a3,
      a4: a4 ?? this.a4,
      a5: a5 ?? this.a5,
      a6: a6 ?? this.a6,
      a7: a7 ?? this.a7,
      a8: a8 ?? this.a8,
      a9: a9 ?? this.a9,
      a10: a10 ?? this.a10,
      a11: a11 ?? this.a11,
      a12: a12 ?? this.a12,
      a13: a13 ?? this.a13,
      a14: a14 ?? this.a14,
      a15: a15 ?? this.a15,
    );
  }
}