Obsolete attribute is ignored in constructor property assignment

[NinoFloris]

Given code like

    System.Text.Json.JsonSerializerOptions(
                    JsonSerializerDefaults.Web,
                    IgnoreNullValues = true)

IgnoreNullValues is obsolete but does not trigger a warning.

Writing System.Text.Json.JsonSerializerOptions().IgnoreNullValues does properly warn.