System.Text.Json.JsonSerializer doesn't serialize properties from derived classes - .net-core

Question

I can't have System.Text.Json.JsonSerializer serializing properties from derived classes. Newtonsoft has no issues doing the job.
namespace TestJson
{
class Program
{
static void Main(string[] args)
{
var myClass = new NewClass2
{
Value1 = "qsd",
ShouldBeSerialized = "why am I not serialized?"
};
// as expected, getting {"ShouldBeSerialized":"why am not serialized?","Value1":"qsd"}
var textJsonSerializedFromTop = System.Text.Json.JsonSerializer.Serialize<NewClass2>(myClass);
// expecting {"ShouldBeSerialized":"why am not serialized?","Value1":"qsd"}
// but getting {"Value1":"qsd"}
var textJsonSerializedFromBase = System.Text.Json.JsonSerializer.Serialize<ClassBase>(myClass);
// as expected, getting {"ShouldBeSerialized":"why am not serialized?","Value1":"qsd"}
var newtonSoftSerializedFromBase = Newtonsoft.Json.JsonConvert.SerializeObject(myClass);
}
}
public class ClassBase
{
public string Value1 { get; set; }
}
public class NewClass2 : ClassBase
{
public string ShouldBeSerialized { get; set; }
}
}
In the previous example to show the actual issue, the solution is straight forward, but in the following one, I have no clue how to manage by not using newtonsoft:
namespace TestJson
{
class Program
{
static void Main(string[] args)
{
var toSerialize =
new[] {
new ClassBase
{
Value1 = "aze"
},
new NewClass2
{
Value1="qsd",
ShouldBeSerialized="why am I not serialized?"
}
};
var textJsonSerialized = System.Text.Json.JsonSerializer.Serialize(toSerialize);
// expecting [{"Value1":"aze"},{"ShouldBeSerialized":"why am not serialized?","Value1":"qsd"}]
// but getting [{"Value1":"aze"},{"Value1":"qsd"}]
Console.WriteLine(textJsonSerialized);
var newtonSoftSerialized = Newtonsoft.Json.JsonConvert.SerializeObject(toSerialize);
// as expected getting [{"Value1":"aze"},{"ShouldBeSerialized":"why am not serialized?","Value1":"qsd"}]
Console.WriteLine(newtonSoftSerialized);
}
}
public class ClassBase
{
public string Value1 { get; set; }
}
public class NewClass2 : ClassBase
{
public string ShouldBeSerialized { get; set; }
}
}