Resolved various failing tests.

src/Umbraco.Infrastructure/Models/ContentEditing/UserInvite.cs

@@ -33,6 +33,7 @@ namespace Umbraco.Web.Models.ContentEditing
             if (UserGroups.Any() == false)
                 yield return new ValidationResult("A user must be assigned to at least one group", new[] { nameof(UserGroups) });
 
+            // TODO: this will need another way of retrieving this setting if and when Configs are removed from Current.
             if (Current.Configs.Security().UsernameIsEmail == false && Username.IsNullOrWhiteSpace())
                 yield return new ValidationResult("A username cannot be empty", new[] { nameof(Username) });
         }