Support for marking all record fields as required by default

[Dzoukr]

Hello, thanks for the amazing work - I am using this library quite a lot. I came across an interesting problem. From the F# perspective, all record fields are required by default, unless marked as option or Nullable<'a>. But generated Swagger/OpenAPI file does not make them all required until I mark them one by one with [<Required>] attribute, which kinda works, but it's a smell.

Can I make it default somehow that all fields are required until marked as option or Nullable<'a>?