DeSjoerd 

Optional values for C# to model omitted values (undefined in javascript) and it has a JsonConvertor to support omitted values in Json.

FluentValidation extensions for OptionalValues.

Support for OptionalValues in schemas for Swashbuckle

DataAnnotations for OptionalValues.

Stand-alone version of the Orchard Eventbus.

Support for OptionalValues in schemas for NSwag and NJsonSchema

T to localize, Package for unit tests

Support for OptionalValues in schemas for ASP.NET Core OpenApi

MVC validation metadata support for OptionalValues.