TF-2934 Fix mailbox name with space only

lib/features/mailbox_creator/domain/exceptions/verify_name_exception.dart

@@ -6,36 +6,32 @@ abstract class VerifyNameException extends Equatable implements Exception {
   static const duplicatedName = 'The name already exists!';
   static const nameContainSpecialCharacter = 'The name cannot contain special characters';
   static const emailAddressInvalid = 'The email address invalid';
+  static const spaceOnlyWithinName = 'The name cannot contain only spaces';
 
   final String? message;
 
   const VerifyNameException(this.message);
+
+  @override
+  List<Object?> get props => [message];
 }
 
 class EmptyNameException extends VerifyNameException {
   const EmptyNameException() : super(VerifyNameException.emptyName);
-
-  @override
-  List<Object> get props => [];
 }
 
 class DuplicatedNameException extends VerifyNameException {
   const DuplicatedNameException() : super(VerifyNameException.duplicatedName);
-
-  @override
-  List<Object> get props => [];
 }
 
 class SpecialCharacterException extends VerifyNameException {
   const SpecialCharacterException() : super(VerifyNameException.nameContainSpecialCharacter);
-
-  @override
-  List<Object> get props => [];
 }
 
 class EmailAddressInvalidException extends VerifyNameException {
   const EmailAddressInvalidException() : super(VerifyNameException.emailAddressInvalid);
+}
 
-  @override
-  List<Object> get props => [];
+class NameWithSpaceOnlyException extends VerifyNameException {
+  const NameWithSpaceOnlyException() : super(VerifyNameException.spaceOnlyWithinName);
 }