core-bundle/src/Resources/contao/dca/tl_files.php
public function syncFiles($href, $label, $title, $class, $attributes)
	{
		return $this->User->hasAccess('f6', 'fop') ? '<a href="'.$this->addToUrl($href).'" title="'.Contao\StringUtil::specialchars($title).'" class="'.$class.'"'.$attributes.'>'.$label.'</a> ' : '';
	}
public function syncFiles($href, $label, $title, $class, $attributes)
	{
		return $this->User->hasAccess('f6', 'fop') ? '<a href="'.$this->addToUrl($href).'" title="'.Contao\StringUtil::specialchars($title).'" class="'.$class.'"'.$attributes.'>'.$label.'</a> ' : '';
	}
Return the sync files button

@param string $href
@param string $label
@param string $title
@param string $class
@param string $attributes

@return string