BaseModel,
        ConfigDict,
        PlainSerializer,
        TypeAdapter,
        WithJsonSchema,
    )

    class FakeNumpyArray:
        def __init__(self):
            self.data = [1.0, 2.0, 3.0]

    FakeNumpyArrayPydantic = Annotated[
        FakeNumpyArray,
        WithJsonSchema(TypeAdapter(list[float]).json_schema()),
        PlainSerializer(lambda v: v.data),
    ]

                # the old field info metadata and only the rest of the attributes
                Field(**field_dict["attributes"]),
            )
            self._type_adapter: TypeAdapter[Any] = TypeAdapter(
                Annotated[annotated_args],  # ty: ignore[invalid-type-form]
                config=self.config,
            )

    def get_default(self) -> Any:
        if self.field_info.is_required():

    pass


@app.post("/items/")
async def create_items(items: ItemList):
    return items

```

FastAPI supports these type annotations and will create a Pydantic `TypeAdapter` for them, so that types can work as normally and there's no need for the custom logic and types in RootModels.

## Use one HTTP operation per function

                    )
                    # Use the fast path (dump_json) when no custom response
                    # class was set and a response field with a TypeAdapter
                    # exists. Serializes directly to JSON bytes via Pydantic's
                    # Rust core, skipping the intermediate Python dict +
                    # json.dumps() step.