code: protected function mapDynamicField(Field $field, \stdClass $rootObject, $path = null)
      {
          $mapping = $this->types[$field->getType()->getTypeValue()];
  
          if ($field->isAList()) {
              $mapping['type'] = 'nested';
          }
  
          $mapping['properties']['string_val'] = $this->applyAnalyzer(
              $mapping['properties']['string_val'], $field, $rootObject, $path
          );
  
          $mapping['properties']['text_val'] = $this->applyAnalyzer(
              $mapping['properties']['text_val'], $field, $rootObject, $path
          );
  
          return $mapping;
      }
docs: @link https://www.elastic.co/guide/en/elasticsearch/reference/current/nested.html
  
  @param Field     $field
  @param \stdClass $rootObject
  @param string    $path
  
  @return array