raw_body = await request.body()
    try:
        data = yaml.safe_load(raw_body)
    except yaml.YAMLError:
        raise HTTPException(status_code=422, detail="Invalid YAML")
    try:
        item = Item.model_validate(data)
    except ValidationError as e:
        raise HTTPException(status_code=422, detail=e.errors(include_url=False))

    new_field.model_config = field.model_config  # type: ignore[attr-defined]
    new_field.field_info = field.field_info
    new_field.allow_none = field.allow_none  # type: ignore[attr-defined]
    new_field.validate_always = field.validate_always  # type: ignore[attr-defined]
    if field.sub_fields:  # type: ignore[attr-defined]
        new_field.sub_fields = [  # type: ignore[attr-defined]

            yield cls.validate

        @classmethod
        def validate(cls, v: Any) -> str:
            logger.warning(
                "email-validator not installed, email fields will be treated as str.\n"
                "To install, run: pip install email-validator"
            )
            return str(v)

        @classmethod
        def _validate(cls, __input_value: Any, _: Any) -> str:

    try:
        from pydantic_core.core_schema import (
            with_info_plain_validator_function as with_info_plain_validator_function,
        )
    except ImportError:  # pragma: no cover
        from pydantic_core.core_schema import (
            general_plain_validator_function as with_info_plain_validator_function,  # noqa: F401
        )

    Required = PydanticUndefined
    Undefined = PydanticUndefined

def get_client():
    from pydantic import BaseModel, ValidationInfo, field_validator

    app = FastAPI()

    class ModelB(BaseModel):
        username: str

    class ModelC(ModelB):
        password: str

    class ModelA(BaseModel):
        name: str
        description: Optional[str] = None
        foo: ModelB

        @field_validator("name")
        def lower_username(cls, name: str, info: ValidationInfo):