code: static Set<Chronology> getAvailableChronologies() {
          initCache();       // force initialization
          HashSet<Chronology> chronos = new HashSet<>(CHRONOS_BY_ID.values());
  
          /// Add in Chronologies from the ServiceLoader configuration
          @SuppressWarnings("rawtypes")
          ServiceLoader<Chronology> loader = ServiceLoader.load(Chronology.class);
          for (Chronology chrono : loader) {
              chronos.add(chrono);
          }
          return chronos;
      }
docs: Returns the available chronologies.
  <p>
  Each returned {@code Chronology} is available for use in the system.
  The set of chronologies includes the system chronologies and
  any chronologies provided by the application via ServiceLoader
  configuration.
  
  @return the independent, modifiable set of the available chronology IDs, not null