protected function _registerBuiltInTypes()
    {
        $this->registerJsonType("boolean", new Types\BoolType(), array("bool"));
        $this->registerJsonType("float", new Types\FloatType());
        $this->registerJsonType("integer", new Types\IntType(), array("int"));
        $this->registerJsonType("string", new Types\StringType());
        $this->registerJsonType("datetime", new Types\DateTimeType());
    }