Implemented the ability to recognize if an input field is null or not present at all

[xperiandri]

Imagine you have an address

type AddressRecord = {
    Line1: AddressLine1 Skippable
    Line2: AddressLine2 voption Skippable
    City: City Skippable
    State: State Skippable
    ZipCode: ZipCode Skippable
}

and you want to patch it (apply changes to only particular fields keeping the other untouched).

Then you can send such an input object

{
  "line1": "New value"
  "line2": null // means clear value
  // skip other properties, means do not change them
}

To support this approach we need to be able to recognize if a field is null or missing and to support converting input values into System.Text.Json.Serialization.Skippable where missing value is Skip, null value is Include None/Include ValueNone (when class constructor parameter is Option/ValueOption and Skip otherwise) and value is Include value

See StarWarsApi for usage sample

[xperiandri]

@njlr @pkese what do you think?

[njlr]

@njlr @pkese what do you think?

LGTM 👍

[pkese]

Yes, it's a good solution. 👍