@Nullable
    List<LanguageRange> acceptLanguages() {
        final List<String> acceptLanguageHeaders = getAll(HttpHeaderNames.ACCEPT_LANGUAGE);
        if (acceptLanguageHeaders.isEmpty()) {
            // TODO(ikhoon): Return an empty list if no accept-language exists in Armeria 2.0
            return null;
        }

        try {
            final List<LanguageRange> acceptLanguages = new ArrayList<>(4);
            for (String acceptLanguage : acceptLanguageHeaders) {
                acceptLanguages.addAll(LanguageRange.parse(acceptLanguage));
            }
            acceptLanguages.sort(comparingDouble(LanguageRange::getWeight).reversed());

            return Collections.unmodifiableList(acceptLanguages);
        } catch (IllegalArgumentException e) {
            // If any port of any of the headers is ill-formed
            return null;
        }
    }
Adds the specified {@code setCookies} with {@link HttpHeaderNames#SET_COOKIE}.
core/src/main/java/com/linecorp/armeria/common/HttpHeadersBase.java