Define how to handle the instantiation policy of the following situations

• the none-serializable property
• property mark with [SerializeReference]

public interface INestClass         
{
}
public class NestClass1 : INestClass
{
    public int Value;
}
[ShowInInspector]
[InstancePolicy(InstancePolicyAttribute.PolicyType.Nullable)]
public NestClass1 NC;
[SerializeReference]         
[InstancePolicy(InstancePolicyAttribute.PolicyType.UsingDerived)]         
public INestClass NestInterface;

PolicyType

• Default: instantiating the object directly
• Nullable: null values are allowed, and instantiation can be selected by clicking the button
• UsingDerived: null values are allowed, and the type of instantiation can be selected by clicking the button