code: public boolean isSet(final Enum option) {
          final OptionHolder holder = options.getHolder(option);
          return holder != null && holder.isSet();
      }
docs: All options are set in application (before application start) and will not change after.
  
  @param option option enum
  @return true if option was manually defined, false when default value used
  @throws IllegalArgumentException if option was not used