chromium/chromeos/components/test/data/onc/valid_cellular_with_apn.onc

{
  "GlobalNetworkConfiguration": {
    "AllowAPNModification": true,
    "AllowCellularHotspot": true,
    "AllowCellularSimLock": true,
    "AllowOnlyPolicyCellularNetworks": false,
    "AllowOnlyPolicyNetworksToAutoconnect": false
  },
  "NetworkConfigurations": [
    {
      "Cellular": {
        "Recommended": [
          "AllowRoaming"
        ],
        "APN": {
            "AccessPointName": "test-apn",
            "Authentication": "",
            "Username": "test-username",
            "Password": "test-password"
        },
        "SMDPAddress": "LPA:1$SMDP.GSMA.COM$00000-00000-00000-000-0001",
      },
      "GUID": "test-Cellular",
      "Name": "test",
      "Type": "Cellular"
    }
  ]
}