bug: Working Service for HTTP gives error with Grpc "type doesn't support gRPC serving"

[EraYaN]

Describe the bug

The difference in bentoml serve and bentoml serve-grpc

This only seems to be the case for class based services. "variable" based ones seem to work just fine.

Log output

2024-04-05T16:15:51+0200 [WARNING] [cli] Converting 'BentoService' to lowercase: 'bentoservice'.
2024-04-05T16:15:51+0200 [DEBUG] [cli] Failed to load bento with v1.2 loader, fallback to old loader
2024-04-05T16:15:51+0200 [DEBUG] [cli] Importing service "service:BentoService" from working dir: "C:\Users\User\source\repos\bento-service\src"
2024-04-05T16:15:52+0200 [DGB] [cli] 'bento_service' imported from source: <Service name='bento_service'>
2024-04-05T16:15:53+0200 [DGB] [cli] Tracking Error: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: certificate has expired (_ssl.c:1006)
Error: [serve] `serve-grpc` failed: <class '_bentoml_sdk.service.factory.Service'> type doesn't support gRPC serving
Traceback (most recent call last):
  File "C:\Users\User\mambaforge\envs\bentoml\Scripts\bentoml-script.py", line 9, in <module>
    sys.exit(cli())
             ^^^^^
  File "C:\Users\User\mambaforge\envs\bentoml\Lib\site-packages\click\core.py", line 1157, in __call__
    return self.main(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\User\mambaforge\envs\bentoml\Lib\site-packages\click\core.py", line 1078, in main
    rv = self.invoke(ctx)
         ^^^^^^^^^^^^^^^^
  File "C:\Users\User\mambaforge\envs\bentoml\Lib\site-packages\click\core.py", line 1688, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\User\mambaforge\envs\bentoml\Lib\site-packages\click\core.py", line 1434, in invoke
    return ctx.invoke(self.callback, **ctx.params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\User\mambaforge\envs\bentoml\Lib\site-packages\click\core.py", line 783, in invoke
    return __callback(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\User\mambaforge\envs\bentoml\Lib\site-packages\bentoml_cli\utils.py", line 385, in wrapper
    raise err from None
  File "C:\Users\User\mambaforge\envs\bentoml\Lib\site-packages\bentoml_cli\utils.py", line 380, in wrapper
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\User\mambaforge\envs\bentoml\Lib\site-packages\click\decorators.py", line 33, in new_func
    return f(get_current_context(), *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\User\mambaforge\envs\bentoml\Lib\site-packages\bentoml_cli\utils.py", line 351, in wrapper
    return_value = func(*args, **kwargs)
                   ^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\User\mambaforge\envs\bentoml\Lib\site-packages\bentoml_cli\env_manager.py", line 122, in wrapper
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\User\mambaforge\envs\bentoml\Lib\site-packages\bentoml_cli\serve.py", line 500, in serve_grpc
    serve_grpc_production(
  File "C:\Users\User\mambaforge\envs\bentoml\Lib\site-packages\simple_di\__init__.py", line 139, in _
    return func(*_inject_args(bind.args), **_inject_kwargs(bind.kwargs))
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\User\mambaforge\envs\bentoml\Lib\site-packages\bentoml\serve.py", line 552, in serve_grpc_production
    raise BentoMLException(f"{type(svc)} type doesn't support gRPC serving")
bentoml.exceptions.BentoMLException: <class '_bentoml_sdk.service.factory.Service'> type doesn't support gRPC serving

To reproduce

from __future__ import annotations

import logging

import numpy as np

import bentoml
import numpy as np

root_logger = logging.getLogger()
root_logger.setLevel(logging.INFO)

bentoml_logger = logging.getLogger("bentoml")
bentoml_logger.setLevel(logging.DEBUG)

@bentoml.service(name="bento_service")
class BentoService():

    def __init__(self) -> None:
       pass

    @bentoml.api #(input=bentoml.io.NumpyNdarray(np.float64,shape=[1,1]), output=bentoml.io.NumpyNdarray(np.float64,shape=[1,1]))
    async def double_it(self, input: np.ndarray) -> np.ndarray:
        result = input * 2
        return result

and then run this:
bentoml serve-grpc --development --verbose

Expected behavior

This should work just like the http serve, and actually start the service.

Environment

bentoml: 1.2.9
python: 3.11.8
platform: Windows 11 x64 23H2