static String toCookieHeader(Collection<? extends Cookie> cookies) {
        return toCookieHeader(true, cookies);
    }
Encodes the specified {@link Cookie}s into a {@code "Cookie"} header value.

@param cookies the {@link Cookie}s to encode.
@return the encoded {@code "Cookie"} header value.

@throws IllegalArgumentException if {@code cookies} is empty.
core/src/main/java/com/linecorp/armeria/common/Cookie.java