JSON Delta Formatter remove operation does not keep the previous value

[nicoguedes]

I've got the following inputs and I'm using the JSON Delta formatter:

            {
                person = new
                {
                    name = "John Doe",
                    dob = DateTime.Now
                },
                addresses = new List<string>() { "address 1", "address 2" }
            };

            dynamic newObject = new
            {
                person = new
                {
                    name = "Patrick",
                },
                addresses = new List<string>() { "address 1", "address 3" }
            };

The response is:

{"path":"/person/dob","op":"remove","from":null,"value":null}

If I were using the default formatter, I would have for the dob field something like that:

 "dob": [
      "2021-10-14T15:41:57.7683884-03:00",
      0,
      0
    ]

I would expect to be able to have the previous value in the JSON Patch response too.

I'm creating my own formatter inheriting from the JsonDeltaFormatter class and overriding this method:

jsondiffpatch.net/Src/JsonDiffPatchDotNet/Formatters/JsonPatch/JsonDeltaFormatter.cs

Line 18 in d0abb0e

protected override void Format(DeltaType type, JsonFormatContext context, JToken delta, JToken leftValue, string key, string leftKey, MoveDestination movedFrom)

More specifically this line, that only takes the context into account, without the delta:

jsondiffpatch.net/Src/JsonDiffPatchDotNet/Formatters/JsonPatch/JsonDeltaFormatter.cs

Line 35 in d0abb0e

FormatDeleted(context);

However, if this is not working as designed I'd rather open a PR.

[MrXander]

I tried to workaround it here:
https://github.com/MrXander/json-diff