Whether the URI is a absolute-path reference.
A relative reference that begins with a single slash character is termed an absolute-path reference.
https://datatracker.ietf.org/doc/html/rfc3986#section-4.2
public static function isAbsolutePathReference(UriInterface $uri) : bool { return $uri->getScheme() === '' && $uri->getAuthority() === '' && isset($uri->getPath()[0]) && $uri->getPath()[0] === '/'; }