origin = get_origin(annotation)
    if origin is Union or origin is UnionType:
        return any(field_annotation_is_complex(arg) for arg in get_args(annotation))

    if origin is Annotated:
        return field_annotation_is_complex(get_args(annotation)[0])

    return (
        _annotation_is_complex(annotation)
        or _annotation_is_complex(origin)
        or hasattr(origin, "__pydantic_core_schema__")

from pydantic_core import CoreSchema as CoreSchema
from pydantic_core import PydanticUndefined, PydanticUndefinedType
from pydantic_core import Url as Url
from typing_extensions import Literal, get_args, get_origin

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

    QueryParams,
    UploadFile,
)
from starlette.requests import HTTPConnection, Request
from starlette.responses import Response
from starlette.websockets import WebSocket
from typing_extensions import Literal, get_args, get_origin

multipart_not_installed_error = (
    'Form data requires "python-multipart" to be installed. \n'
    'You can install "python-multipart" with: \n\n'
    "pip install python-multipart\n"
)