default String toCookieHeader() {
        return toCookieHeader(true);
    }
Encodes this {@link Cookie} into a single {@code "Cookie"} header value.
Note that you must use {@link #toCookieHeader(Collection)} when encoding more than one {@link Cookie},
because it is prohibited to send multiple {@code "Cookie"} headers in an HTTP request,
according to <a href="https://datatracker.ietf.org/doc/html/rfc6265#section-5.4">RFC 6265</a>.

@return a single RFC 6265-style {@code "Cookie"} header value.
core/src/main/java/com/linecorp/armeria/common/Cookie.java