final void contentType(MediaType contentType) {
        requireNonNull(contentType, "contentType");
        cache.put(HttpHeaderNames.CONTENT_TYPE, contentType);
        setWithoutNotifying(HttpHeaderNames.CONTENT_TYPE, contentType.toString());
    }
Adds the specified {@code setCookies} with {@link HttpHeaderNames#SET_COOKIE}.
core/src/main/java/com/linecorp/armeria/common/HttpHeadersBase.java