code: @Nonnull
    public CacheControlBuilder setSharedMaxAge (@Nonnull final TimeUnit eTimeUnit, final long nDuration)
    {
      return setSharedMaxAgeSeconds (eTimeUnit.toSeconds (nDuration));
    }
docs: Set the maximum age for shared caches relative to the request time. Similar
  to max-age, except that it only applies to shared (e.g., proxy) caches.
  
  @param eTimeUnit
  {@link TimeUnit} to use
  @param nDuration
  The duration in the passed unit
  @return this