System.Text.Json:如何将对象序列化为具有键的嵌套子对象？

public class ParentObject
{
    public string Key1 { get; set; }
    public NestedObject Key2 { get; set; }
}

public class NestedObject
{
    public string NestedKey1 { get; set; }
    public string NestedKey2 { get; set; }
}

ParentObject parentObj = new ParentObject
{
    Key1 = "Value1",
    Key2 = new NestedObject
    {
        NestedKey1 = "NestedValue1",
        NestedKey2 = "NestedValue2"
    }
};

string json = JsonSerializer.Serialize(parentObj);

{
    "Key1": "Value1",
    "Key2": {
        "NestedKey1": "NestedValue1",
        "NestedKey2": "NestedValue2"
    }
}