Jarves\Admin\ObjectCrud::getItemsSelection PHP Method

    protected function getItemsSelection($fields = null)
    {
        $fields = Tools::listToArray($fields);
        if ($fields) {
            return $fields;
        }
        if (!$fields && $this->getColumns()) {
            $fields = [];
            foreach ($this->getColumns() as $field) {
                $fields[] = $field->getId();
            }
        }
        $fields = array_merge($fields, Tools::listToArray($this->getObjectDefinition()->getDefaultSelection()));
        return $this->applyDefaultSelection($fields);
    }