code: public function visit(Criterion $criterion, CriterionVisitor $subVisitor = null)
      {
          $searchFields = $this->getSearchFields($criterion);
  
          if (empty($searchFields)) {
              throw new InvalidArgumentException(
                  '$criterion->target',
                  "No searchable fields found for the given criterion target '{$criterion->target}'."
              );
          }
  
          $queries = [];
          foreach ($searchFields as $name => $fieldType) {
              $preparedValue = $this->toString($this->mapSearchFieldValue($criterion->value, $fieldType));
  
              // Check if there is user supplied wildcard or not
              if (strpos($preparedValue, '*') !== false) {
                  $queries[] = $name . ':' . $this->escapeExpressions($preparedValue, true);
              } else {
                  $queries[] = $name . ':"' . $this->escapeQuote($preparedValue, true) . '"';
              }
          }
  
          return '(' . implode(' OR ', $queries) . ')';
      }
docs: Map field value to a proper Solr representation.
  
  @throws \eZ\Publish\Core\Base\Exceptions\InvalidArgumentException If no searchable fields are found for the given criterion target.
  
  @param \eZ\Publish\API\Repository\Values\Content\Query\Criterion $criterion
  @param \EzSystems\EzPlatformSolrSearchEngine\Query\CriterionVisitor $subVisitor
  
  @return string