Serializer doesn't serialize XmlNodeName property from UnknownLiveDevice

[luizen]

For some reason, that property is not being serialized to JSON when outputting to console.
It is, though, being stored and fetched correctly to/from database.

[luizen]

dotnet/runtime#31742

dotnet/runtime#29937

https://github.com/dotnet/corefx/blob/fbb8b5c4b9566ba81596aa35f42b71bbda601528/src/System.Text.Json/tests/Serialization/CustomConverterTests.Polymorphic.cs#L11-L147

https://github.com/dotnet/corefx/blob/fbb8b5c4b9566ba81596aa35f42b71bbda601528/src/System.Text.Json/tests/Serialization/CustomConverterTests.Polymorphic.cs#L159-L218