code: public JsonArray getPropAsJsonArray(String key) {
      JsonElement jsonElement = this.jsonParser.parse(getProp(key));
      Preconditions.checkArgument(jsonElement.isJsonArray(),
          "Value for key " + key + " is malformed, it must be a JsonArray: " + jsonElement);
      return jsonElement.getAsJsonArray();
    }
docs: Get the value of a property as a {@link JsonArray}.
  
  @param key property key
  @return {@link JsonArray} value associated with the key