Union,
    cast,
    get_args,
    get_origin,
)

from fastapi._compat import lenient_issubclass, shared
from fastapi.openapi.constants import REF_TEMPLATE
from fastapi.types import IncEx, ModelNameMap, UnionType
from pydantic import BaseModel, ConfigDict, Field, TypeAdapter, create_model
from pydantic import PydanticSchemaGenerationError as PydanticSchemaGenerationError

    """Check if field type is a Union where all members are BaseModel subclasses."""
    from fastapi.types import UnionType

    origin = get_origin(field_type)

    # Check if it's a Union type (covers both typing.Union and types.UnionType in Python 3.10+)
    if origin is not Union and origin is not UnionType:
        return False

    union_args = get_args(field_type)

    for arg in union_args: