Elementor\TemplateLibrary\Manager::register_source PHP Метод

    public function register_source($source_class, $args = [])
    {
        if (!class_exists($source_class)) {
            return new \WP_Error('source_class_name_not_exists');
        }
        $source_instance = new $source_class($args);
        if (!$source_instance instanceof Source_Base) {
            return new \WP_Error('wrong_instance_source');
        }
        $this->_registered_sources[$source_instance->get_id()] = $source_instance;
        return true;
    }