Some constants were deprecated and replaced with enums

CasHelper::CA_* constants deprecated in favour of SslCertificateVerification enum

CasHelper::CA_DEFAULT, CasHelper::CA_CUSTOM, CasHelper::CA_NONE constants are deprecated and replaced with this enum:

enum SslCertificateVerification: int implements OptionsInterface {
  case Default = 0;
  case Custom = 1;
  case None = 2;
  public static function getAsOptions(): array {
    return [
      SslCertificateVerification::Default->value => t("Verify using your web server's default certificate authority (CA) chain."),
      SslCertificateVerification::None->value => t('Do not verify. (Note: this should NEVER be used in production.)'),
      SslCertificateVerification::Custom->value => t('Verify using a specific CA certificate. Use the field below to provide path (recommended).'),
    ];
  }
}

CasHelper::GATEWAY_* constants deprecated in favour of GatewayMethod enum

CasHelper::GATEWAY_SERVER_SIDE, CasHelper::GATEWAY_CLIENT_SIDE constants are deprecated in favour of this enum:

enum GatewayMethod: string implements OptionsInterface {
  case ServerSide = 'server_side';
  case ClientSide = 'client_side';
  public static function getAsOptions(): array {
    return [
      GatewayMethod::ServerSide->value => t('Server-side redirect. Faster, but disables page caching on configured paths.'),
      GatewayMethod::ClientSide->value => t('Client-side redirect (using JavaScript). Slower, but works with all page caching. Not compatible with "Every page request" option above.'),
    ];
  }
}

CasHelper::EVENT_* event constants deprecated in favour of event class fully-qualified name

Constants CasHelper::EVENT_PRE_USER_LOAD, CasHelper::EVENT_PRE_USER_LOAD_REDIRECT, CasHelper::EVENT_PRE_REGISTER, CasHelper::EVENT_PRE_LOGIN, CasHelper::EVENT_PRE_REDIRECT, CasHelper::EVENT_PRE_VALIDATE_SERVER_CONFIG, CasHelper::EVENT_PRE_VALIDATE, CasHelper::EVENT_POST_VALIDATE, CasHelper::EVENT_POST_LOGIN event constants are deprecated in favour of event class fully-qualified name

For instance, instead of CasHelper::EVENT_PRE_LOGIN, subscribers should use CasPreLoginEvent::class

CasLoginException constants deprecated in favour of CasLoginExceptionType enum

CasLoginException::NO_LOCAL_ACCOUNT, CasLoginException::SUBSCRIBER_DENIED_REG, CasLoginException::ACCOUNT_BLOCKED, CasLoginException::SUBSCRIBER_DENIED_LOGIN, CasLoginException::ATTRIBUTE_PARSING_ERROR, CasLoginException::USERNAME_ALREADY_EXISTS, CasLoginException::ADMIN_APPROVAL_REQUIRED constants are deprecated in favour of this enum:

enum CasLoginExceptionType: string {
  case Unknown = '';
  case NoLocalAccount = 'message_no_local_account';
  case SubscriberDeniedRegistration = 'message_subscriber_denied_reg';
  case AccountBlocked = 'message_account_blocked';
  case SubscriberDeniedLogin = 'message_subscriber_denied_login';
  case AttributeParsingError = 'message_validation_failure';
  case UsernameAlreadyExists = 'message_username_already_exists';
  case AdminApprovalRequired = '[no message]';
}

CasUserManager::EMAIL_ASSIGNMENT_* constants deprecated in favour of EmailAssignment enum

CasUserManager::EMAIL_ASSIGNMENT_STANDARD, CasUserManager::EMAIL_ASSIGNMENT_ATTRIBUTE are deprecated in favour of this enum:

enum EmailAssignment: int implements OptionsInterface {
  case Standard = 0;
  case FromAttribute = 1;
  public static function getAsOptions(): array {
    return [
      EmailAssignment::Standard->value => t('Use the CAS username combined with a custom domain name you specify.'),
      EmailAssignment::FromAttribute->value => t("Use a CAS attribute that contains the user's complete email address."),
    ];
  }
}