Serialization of Nullable<AnnualDate> with System.Text.Json

[Daniel García Rubio]

Using the preview of System.Text.Json serialization, and Asp.Net Core 3.1, I'm getting a default serialization for nullable AnnualDate values when they are not null:

{
    "annualDate": {
        "month": 1,
        "day": 1
    },
    "nullableAnnualDateWithValue": {
        "hasValue": true,
        "value": {
            "month": 1,
            "day": 1
        }
    },
    "nullableAnnualDateWithoutValue": null
}

This is different to other composite values such as Interval, which serializes as follows:

{
    "interval": {
        "start": "1970-01-01T00:00:00Z",
        "end": "1970-01-01T00:00:00Z"
    },
    "nullableIntervalWithValue": {
        "start": "1970-01-01T00:00:00Z",
        "end": "1970-01-01T00:00:00Z"
    },
    "nullableIntervalWithoutValue": null
}

Is there any issue preventing the AnnualDate struct being serialized like the others?

[Jon Skeet]

On mobile so can't check right now, but my guess is that we don't have an AnnualDate serializer.