class DoubleJsonDeserializer : JsonDeserializer<Double> {

  override fun deserialize(json: JsonElement, typeOfT: Type?, context: JsonDeserializationContext?): Double {
    if (json is JsonPrimitive && json.isNumber) {
      return json.asDouble
    } else if (json is JsonNull) {
      return Double.NaN
    } else
      throw IllegalArgumentException("Cannot deserialize other type than json primitive")
  }
}

internal fun provideDeserializerGson(): Gson = GsonBuilder()
      .registerTypeAdapter(Double::class.java, DoubleJsonDeserializer())
      .create()