Why is this type annotation not showing up in FastAPI?

This is one of the endpoints in my FastAPI application:

@router.get("/", response_model=Page[DeviceConfigSchemaOUT])
async def get_device_configs(
    search: str | None = None,
    page: int = 1,
    size: int = 50,
) -> Any:
    ...

Which shows up like this in Swagger:

Why is there no type on the search parameter? I tried changing the declaration to an Annotation and manually specifying the type, but the result stays the same. This is using the latest FastAPI version 109.2 and Python 3.12.1.

It seems to be an issue in Pydantic 2 and FastAPI but there is a workaround as discussed in FastAPI discussions (link):

from pydantic.json_schema import SkipJsonSchema

@router.get("/", response_model=Page[DeviceConfigSchemaOUT])
async def get_device_configs(
    search: str | SkipJsonSchema[None] = None,
    page: int = 1,
    size: int = 50,
) -> Any:
    ...