code: public boolean isUsed(final Enum option) {
          final OptionHolder holder = options.getHolder(option);
          return holder != null && holder.isUsed();
      }
docs: Option usage tracked when option read by either
  {@linkplain ru.vyarus.dropwizard.guice.module.installer.bundle.GuiceyBootstrap#option(Enum) bundle} or
  from {@linkplain Options#get(Enum) guice service}. Option may be read in any time of application life so
  used value may change over time (even new options could appear for reporting).
  
  @param option option enum
  @return true if option was read, false if option set but never used
  @throws IllegalArgumentException if option was not used