How can we use the contains() method in a list of complex objects in Dart?

Question

I have a list made up of complex objects : here is the definition of the class :

class Eleve {
  final String classeCode;
  final String email;
  final String userId;
  final String avatar;
  final List defisProf;

  const Eleve(
      {required this.classeCode,
      required this.email,
      required this.userId,
      required this.avatar,
      required this.defisProf});

  Map<String, dynamic> toMap() => {
        'email': email,
        'classeCode': classeCode,
        'userId': userId,
        'avatar': avatar,
        'defisProf': defisProf,
      };

  factory Eleve.fromMap(Map data) => Eleve(
        classeCode: data['classeCode'] ?? '',
        email: data['email'] ?? '',
        userId: data['userId'] ?? '',
        avatar: data['avatar'] ?? '',
        defisProf: data['defisProf'] ?? '',
      );
}

I would like to check if the list named _mesClasses contains an Eleve whose userId is equal to a certain value.

I have a feeling that I should redefine / override the method Contains for the Eleve type... but I don't know how...

Can someone help ?