chromium/chromeos/components/test/data/onc/shill_cellular.json

{
  "AutoConnect": true,
  "Type": "cellular",
  "Cellular.AllowRoaming": true,
  "Cellular.APN": {
    "apn": "test-apn",
    "authentication": "",
    "username": "test-username",
    "password": "test-password"
  }
}