Best alternative for deprecated query engine

sllm = llm.as_structured_llm(output_cls)

index.as_query_engine(llm=sllm)

pydantic_core._pydantic_core.ValidationError: 1 validation error for StructuredLLM
worker-1                | output_cls
worker-1                |   Input should be a subclass of BaseModel [type=is_subclass_of, input_value=<class 'models.MyCustomModel'>, input_type=ModelMetaclass]

from pydantic.v1 import BaseModel as BaseModelV1
from pydantic.v1 import Field as FieldV1

class MyCustomModel(BaseModelV1):
    test: str = FieldV1(..., description="Test")