Incorrect parsing of null as nullable enum value serialized as strings

Consider the following schema definition (which passes validation with the openapitools/openapi-generator-cli container image):

// [...]
          "deviceEncryptionKeyScheme": {
            "$ref": "#/components/schemas/DeviceEncryptionKeyScheme",
            "nullable": true  // <-- nullability declared
          },

// [...]
      "DeviceEncryptionKeyScheme": {
        "enum": ["Default8"],
        "type": "string"
      },

It looks as if openapi-python-client version 0.23.1 supports deserialization with the deviceEncryptionKeyScheme property being unset, but not it being null:

        _device_encryption_key_scheme = d.pop("deviceEncryptionKeyScheme", UNSET)
        device_encryption_key_scheme: Union[Unset, DeviceEncryptionKeyScheme]
        if isinstance(_device_encryption_key_scheme, Unset):
            device_encryption_key_scheme = UNSET
        else:
            device_encryption_key_scheme = DeviceEncryptionKeyScheme(_device_encryption_key_scheme)

This looks like a bug to me.

Reproduce el caso de enum nullable del issue usando el comportamiento de openapi-python-client 0.23.1 y el código de deserialización generado que se muestra. Empieza por el manejo de deviceEncryptionKeyScheme después de d.pop; compara la ruta UNSET con la ruta null. El trabajo estará terminado cuando un valor explícitamente null se deserialice correctamente, mientras que una propiedad no establecida siga representándose como UNSET.