The discriminator should follow the following designs:

1. the base model should be abstract.
2. the discriminator property is internal by default. There is an option that could make it public.
3. the ctor of base model is protected. The discriminator property is passed in in this ctor.
4. the derived models inherit from the base model, and assign value to the discriminator property in its initialization ctor.
5. the serialization ctor takes the discriminator as a parameter
6. an extra internal class (maybe sealed) is created which inherits from the base model with the name of Unknown{BaseModelName} to represent the case that we get an unknown value of the discriminator from the service.