final StringBuilder newHeaderValueBuffer() {
        final StringBuilder buf = new StringBuilder(40);
        if (noCache) {
            buf.append(", no-cache");
        }
        if (noStore) {
            buf.append(", no-store");
        }
        if (noTransform) {
            buf.append(", no-transform");
        }
        if (maxAgeSeconds >= 0) {
            buf.append(", max-age=").append(maxAgeSeconds);
        }
        return buf;
    }
Returns a new {@link StringBuilder} with the common directives appended.
Note that the first two characters ({@code ", "} must be stripped.
core/src/main/java/com/linecorp/armeria/common/CacheControl.java