src/Http/Formatting/ResponseHeaderFormatter.php
public function setCookie(HttpHeaders $headers, Cookie $cookie): void
    {
        $headers->add('Set-Cookie', $this->getSetCookieHeaderValue($cookie), true);
    }
public function setCookie(HttpHeaders $headers, Cookie $cookie): void
    {
        $headers->add('Set-Cookie', $this->getSetCookieHeaderValue($cookie), true);
    }
Sets a cookie in the headers

@param HttpHeaders $headers The headers to set the cookie in
@param Cookie $cookie The cookie to set
@throws RuntimeException Thrown if the set cookie header's hash key could not be calculated