'#description'=>$this->t('Enable Referrer-Policy HTTP response header. This affects the Referer HTTP header for outgoing requests and navigations. More information is available at the <a href=":spec">@spec</a> page.',$args),
];
// Referrer-Policy policy selection.
$items=[
$this->t('no-referrer - No referrer information will be sent.'),
$this->t('no-referrer-when-downgrade - No referrer information will be sent when navigating from HTTPS to HTTP.'),
$this->t('same-origin - Referrer information is sent only with requests to the same origin.'),
$this->t('origin - This will strip any path information from the referrer information.'),
$this->t('strict-origin - Like no-referrer-when-downgrade, but sends only the origin.'),
$this->t('origin-when-cross-origin - Sends full referrer information with same-origin requests, and origin only with cross-origin requests.'),
$this->t('strict-origin-when-cross-origin - Sends full referrer information with same-origin requests, origin only with cross-origin requests, and no referrer information if downgrading from https to http.'),
$this->t('unsafe-url - Sends full referrer information with all requests; as the name implies, this is not safe.'),
$this->t('"" (empty string) - Default to no-referrer-when-downgrade unless a higher-level policy has been defined elsewhere.'),