Parsing error in Google GeoLocate JSON API example

Google changed its GeoLocation api and didn't update the documentation?

I followed their example code verbatim on the next page

https://developers.google.com/maps/documentation/geolocation/intro

I have pasted the sample request into a file on my system called ex.json. I double checked that my Google Geolocation API is enabled and ran the following curl command

curl -d ex.json -H "Content-Type: application/json" -i "https://www.googleapis.com/geolocation/v1/geolocate?key=[My key, yes I pasted my actual key in]"

      

        
        
        
      

    

I got the following answer

{
 "error": {
  "errors": [
   {
    "domain": "global",
    "reason": "parseError",
    "message": "Parse Error"
   }
  ],
  "code": 400,
  "message": "Parse Error"
 }
}

      

        
        
        
      

    

Which according to the documentation means there is something wrong with the json example they provided. Just for completeness, the json sample looks like

{
 "homeMobileCountryCode": 310,
 "homeMobileNetworkCode": 260,
 "radioType": "gsm",
 "carrier": "T-Mobile",
 "cellTowers": [
  {
   "cellId": 39627456,
   "locationAreaCode": 40495,
   "mobileCountryCode": 310,
   "mobileNetworkCode": 260,
   "age": 0,
   "signalStrength": -95
  }
 ],
 "wifiAccessPoints": [
  {
   "macAddress": "01:23:45:67:89:AB",
   "signalStrength": 8,
   "age": 0,
   "signalToNoiseRatio": -65,
   "channel": 8
  },
  {
   "macAddress": "01:23:45:67:89:AC",
   "signalStrength": 4,
   "age": 0
  }
 ]
}

      

        
        
        
      

    

JsonLint has verified that it is valid Json and the documentation says that all fields are optional. What am I missing, was some required field added after writing the documentation?