src/ExternalURLField.php
public function setValue($url)
    {
        if ($url) {
            $url = $this->rebuildURL($url);
        }
        parent::setValue($url);
    }
public function setValue($url)
    {
        if ($url) {
            $url = $this->rebuildURL($url);
        }
        parent::setValue($url);
    }
Rebuild url on save
@param string $url