anchor.diff:  }
   
   class Contact {
  -  Contact(
  -      {this.givenName,
  -      this.middleName,
  -      this.prefix,
  -      this.suffix,
  -      this.familyName,
  -      this.company,
  -      this.jobTitle,
  -      this.emails,
  -      this.phones,
  -      this.postalAddresses,
  -      this.avatar});
  -
  -  String identifier,
  -      displayName,
  -      givenName,
  -      middleName,
  -      prefix,
  -      suffix,
  -      familyName,
  -      company,
  -      jobTitle;
  +  Contact({
  +    this.givenName,
  +    this.middleName,
  +    this.prefix,
  +    this.suffix,
  +    this.familyName,
  +    this.company,
  +    this.jobTitle,
  +    this.emails,
  +    this.phones,
  +    this.postalAddresses,
  +    this.avatar,
  +    this.birthday,
  +  });
  +
  +  String identifier, displayName, givenName, middleName, prefix, suffix, familyName, company, jobTitle;
     Iterable<Item> emails = [];
     Iterable<Item> phones = [];
     Iterable<PostalAddress> postalAddresses = [];
     Uint8List avatar;
  +  DateTime birthday;
   
     String initials() {
       return ((this.givenName?.isNotEmpty == true ? this.givenName[0] : "") +
  
positive.code:         this.middleName == other.middleName &&
          this.prefix == other.prefix &&
          this.suffix == other.suffix &&
          DeepCollectionEquality.unordered().equals(this.phones, other.phones) &&
          DeepCollectionEquality.unordered().equals(this.emails, other.emails) &&
          DeepCollectionEquality.unordered()
  
negative.code:     postalAddresses = (m["postalAddresses"] as Iterable)
          ?.map((m) => PostalAddress.fromMap(m));
      avatar = m["avatar"];
      try {
        birthday = DateTime.parse(m["birthday"]);
      } catch (e) {
        birthday = null;
      }
    }
  
    static Map _toMap(Contact contact) {
  