protected function filter()
    {
        $lists = [
            'listCompetitions',
            'listCountries',
            'listEvents',
            'listEventTypes',
            'listMarketTypes',
            'listVenues',
            'listMarketCatalogue'
        ];

        if (in_array($this->method, $lists) && empty($this->params[ 'filter' ])) {
            $this->params[ 'filter' ] = new \stdClass;
        }
    }