Firebase Admin SDK with Java whether support workload identity federation or not

[Frotly Song]

I am using java admin sdk version 6.8.1 for backend, I  am useing workload identity federation instead of the service account key json file. But I get the following message: Please ask the firehase whether support workload identity federation  or not

Caused by: com.google.api.client.http.HttpResponseException: 500 Internal Server Error
{
  "error": {
    "code": 500,
    "message": "Authentication backend unknown error.",
    "status": "UNKNOWN"
  }
}