silverstripe-cms/code/Forms/SiteTreeURLSegmentField_Readonly.php

<?php

namespace SilverStripe\CMS\Forms;

/**
 * Readonly version of a site tree URL segment field
 */
class SiteTreeURLSegmentField_Readonly extends SiteTreeURLSegmentField
{
    protected $readonly = true;

    public function performReadonlyTransformation()
    {
        return clone $this;
    }
}