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

{
  "GlobalNetworkConfiguration":{
    "AllowOnlyPolicyNetworksToAutoconnect": true,
    "DisableNetworkTypes": ["Cellular", "Ethernet", "WiFi"]
  },
  "NetworkConfigurations":[
    {
      "Ethernet":{
        "Authentication":"None"
      },
      "GUID":"guid",
      "Name":"name",
      "Type":"Ethernet"
    }
  ]
}