code: public <T extends CacheSpec<K, V>> T expiresAfterWrite(String duration) {
        this.expiresAfterWrite = convertStringToTime(duration);
        return Cast.as(this);
     }
docs: The time in milliseconds after write that an item is removed
  
  @param <T>      the type parameter
  @param duration duration is a string in the form d+[dhms] where d is days, h is hours, m is minutes, and s is
  seconds
  @return This cache spec