eZ\Publish\Core\Search\Elasticsearch\Content\CriterionVisitor\CustomField\CustomFieldIn::canVisit PHP Method

    public function canVisit(Criterion $criterion)
    {
        return $criterion instanceof Criterion\CustomField && (($criterion->operator ?: Operator::IN) === Operator::IN || $criterion->operator === Operator::EQ || $criterion->operator === Operator::CONTAINS);
    }