HttpStatus status() {
        final HttpStatus status = (HttpStatus) cache.get(HttpHeaderNames.STATUS);
        if (status != null) {
            return status;
        }

        final String statusStr = get(HttpHeaderNames.STATUS);
        checkState(statusStr != null, ":status header does not exist.");
        final HttpStatus parsed = HttpStatus.valueOf(statusStr);
        cache.put(HttpHeaderNames.STATUS, parsed);
        return parsed;
    }
Adds the specified {@code setCookies} with {@link HttpHeaderNames#SET_COOKIE}.
core/src/main/java/com/linecorp/armeria/common/HttpHeadersBase.java