/me request is only valid with delegated authentication flow

Question

I'm getting the error below when accessing data using Microsoft Graph API:

{"ServerInfo":{"DataCenter":"South XXX","Slice":"E","Ring":"2","ScaleUnit":"002","RoleInstance":"M*******70"}}
{
  "error": {
    "code": "BadRequest",
    "message": "/me request is only valid with delegated authentication flow.",
    "innerError": {
      "date": "2024-03-14T02:17:32",
      "request-id": "***********************",
      "client-request-id": "***********************"
    }
  }
}

I am writing the Java client to access the user mailbox; IMAP plain authentication is blocked, hence trying with Microsoft Graph api.

Given the user.read mail. Read mail. Send permissions.