private Cookies getCookie(AsciiString cookieHeaderName, Function<List<String>, Cookies> cookiesParser) {
        @SuppressWarnings("unchecked")
        final Iterable<Cookie> cookies = (Iterable<Cookie>) cache.get(cookieHeaderName);
        if (cookies == null) {
            // Cache miss. Check the container values.
            final List<String> cookiesString = getAll(cookieHeaderName);
            if (cookiesString.isEmpty()) {
                final Cookies emptyCookies = Cookies.of();
                cache.put(cookieHeaderName, emptyCookies);
                return emptyCookies;
            } else {
                final Cookies parsedCookies = cookiesParser.apply(cookiesString);
                cache.put(cookieHeaderName, parsedCookies);
                return parsedCookies;
            }
        }

        if (cookies instanceof Cookies) {
            return (Cookies) cookies;
        } else {
            final Cookies immutableCookies = Cookies.of(cookies);
            // Make the cached cookies immutable.
            cache.put(cookieHeaderName, immutableCookies);
            return immutableCookies;
        }
    }
Adds the specified {@code setCookies} with {@link HttpHeaderNames#SET_COOKIE}.
core/src/main/java/com/linecorp/armeria/common/HttpHeadersBase.java