references.
    """
    app = FastAPI()
    client = TestClient(app)
    app.post("/endpoint")(passthrough(forwardref_method))
    app.post("/endpoint2")(passthrough(passthrough(forwardref_method)))
    with client:
        response = client.post("/endpoint", json={"input": {"x": 0}})
        response2 = client.post("/endpoint2", json={"input": {"x": 0}})

from pydantic import BaseModel


def forwardref_method(input: "ForwardRefModel") -> "ForwardRefModel":
    return ForwardRefModel(x=input.x + 1)


class ForwardRefModel(BaseModel):