code: public final Cache2kBuilder<K, V> with(ConfigurationSectionBuilder<? extends ConfigurationSection>... sectionBuilders) {
      for (ConfigurationSectionBuilder<? extends ConfigurationSection> b : sectionBuilders) {
        config().getSections().add(b.buildConfigurationSection());
      }
      return this;
    }
docs: Add a new configuration sub section.
  
  @see org.cache2k.configuration.ConfigurationWithSections