ListBuilder/DynamicListBuilder.php
protected function getMediaUrls($value)
    {
        if (is_string($value)) {
            return $this->getMediaUrl($value);
        }

        if (is_array($value)) {
            foreach ($value as $key => $mediaId) {
                $value[$key] = $this->getMediaUrl($mediaId);
            }

            return implode($this->delimiter, $value);
        }

        return $this->toString($value);
    }
protected function getMediaUrls($value)
    {
        if (is_string($value)) {
            return $this->getMediaUrl($value);
        }

        if (is_array($value)) {
            foreach ($value as $key => $mediaId) {
                $value[$key] = $this->getMediaUrl($mediaId);
            }

            return implode($this->delimiter, $value);
        }

        return $this->toString($value);
    }
Get media urls.

@param string $value

@return string