code: func (converter PatternToListConverter) Convert(value interface{}, item AttributeAccessor) (interface{}, error) {
  	result := []string{}
  	i := 0
  	for {
  		key := AttributeExpression(strings.Replace(converter.pattern, "?", strconv.Itoa(i), 1))
  		if v := item.Get(key); v != nil {
  			result = append(result, v.(string))
  		} else {
  			break
  		}
  		i++
  	}
  	return result, nil
  }
docs: // Convert converts all fields from the given item that match this RegexpConverter's pattern, and returns an array of matching values as string