Incorrect value get stored in surname field

[amrita-shrestha]

Describe the bug

When creating a user, the surname field is incorrectly populated with the value of onPremisesSamAccountName (i.e., the username) instead of extracting the actual last name from the displayName.

Steps to reproduce

1. create user

curl -vk -X POST -u admin:admin https://localhost:9200/graph/v1.0/users \
-H "Content-Type: application/json" \
-d '{
  "onPremisesSamAccountName": "hope",
  "displayName": "romi shrestha",
  "mail": "[email protected]",
  "passwordProfile": {
    "password": "1234"
  }
}'

2. Then we get a response

{
    "displayName": "romi shrestha",
    "id": "eeeca5f4-50bd-4863-8d4b-0b53234bae46",
    "mail": "[email protected]",
    "onPremisesSamAccountName": "hope",
    "surname": "hope",
    "userType": "Member"
}

Expected behavior

surname should be "shrestha" — the last name parsed from displayName.

Actual behavior

surname is "hope" — incorrectly using the value of onPremisesSamAccountName.

Setup

Please describe how you started the server and provide a list of relevant environment variables or configuration files.

OCIS_version=7.1.2+12415ad52
Web client version=11.3.1

Additional context

Add any other context about the problem here.