code: def test_nested_json(self):
      @Model.register("fake-model-4")
      class FakeModel(Model):
          """
          This is a fake model with a docstring.
  
          # Parameters
  
          fake_param1: str
          fake_param2: int
          """
  
          def forward(self, **kwargs):
              return {}
  
      model_card = ModelCard.from_params(
          Params(
              {
                  "id": "this-fake-model",
                  "registered_model_name": "fake-model-4",
                  "model_details": {
                      "description": "This is the fake model trained on a dataset.",
                      "paper": {
                          "title": "paper name",
                          "url": "paper link",
                          "citation": "test citation",
                      },
                  },
                  "training_data": {
                      "dataset": {
                          "name": "dataset 1",
                          "url": "dataset url",
                      }
                  },
              }
          )
      )
  
      assert isinstance(model_card.model_details.paper, Paper)
      assert model_card.model_details.paper.url == "paper link"
      assert model_card.training_data.dataset.name == "dataset 1"
  
file_path: allennlp/tests/common/model_card_test.py
imports: from allennlp.common.params import Params
  from allennlp.common.testing import AllenNlpTestCase
  from allennlp.common.model_card import ModelCard, ModelUsage, IntendedUse, Paper
  from allennlp.models import Model
label_desc: Use image node_id 6 for calling the TestPretrainedModelConfiguration obj's underlying member method code with example usage: obj.test_nested_json() and returns: dict