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