code: protected Double getDouble(final String key, final JSONObject jsonObject) {
      Double value = null;
      if(hasKey(key, jsonObject)) {
        try {
          value = jsonObject.getDouble(key);
        }
        catch(JSONException e) {
          LOGGER.error("Could not get Double from JSONObject for key: " + key, e);
        }
      }
      return value;
    }
docs: Check to make sure the JSONObject has the specified key and if so return
  the value as a double. If no key is found null is returned.
  
  @param key name of the field to fetch from the json object
  @param jsonObject object from which to fetch the value
  
  @return double value corresponding to the key or null if key not found