authentication_protocol property of sign-ins events is always an empty list

Describe the bug

When accessing a sign-in event, for example via audit_logs.sign_ins.get() the authentication_protocol property is always an empty list ([]).

If you look at the same sign-in event in Entra ID or Graph Explorer, the field authenticationProtocol is properly filled.

Expected behavior

The authentication_protocol property should contain one of the allowed values. See https://learn.microsoft.com/en-us/graph/api/resources/signin?view=graph-rest-beta#properties -> authenticationProtocol

How to reproduce

Run

import asyncio
from azure.identity.aio import ClientSecretCredential
from msgraph_beta import GraphServiceClient

credential = ClientSecretCredential(
    'tenant_id',
    'client_id',
    'client_secret'
)

scopes = ['https://graph.microsoft.com/.default']
graph_client = GraphServiceClient(credential, scopes=scopes)

async def get_signins()-> None:
    signins =await graph_client.audit_logs.sign_ins.get()
    for signin in signins.value:
        print(signin.authentication_protocol)


asyncio.run(get_signins())

and compare it to the authenticationProtocol field in the output of https://graph.microsoft.com/beta/auditLogs/signIns

SDK Version

1.51.0

Latest version known to work for scenario above?

No response

Known Workarounds

No response

Debug output

Configuration

• OS: Ubuntu 22.04
• architecture: x86_64

Other information

I suspect the usage of get_collection_of_enum_values() instead of get_enum_value() to be the reason for this:
https://github.com/microsoftgraph/msgraph-beta-sdk-python/blob/a606d0365c39a5c2e5f658841a1a7c58d270438b/msgraph_beta/generated/models/sign_in.py#L295

Start with the generated models/sign_in.py location linked in the issue, especially the authentication_protocol handling around line 295. Run the provided sign-in retrieval example and compare the SDK value with the Graph beta response; done means authentication_protocol contains the returned allowed value instead of an empty list.