code: private static MonetaryCurrenciesSingletonSpi MONETARY_CURRENCIES_SINGLETON_SPI() {
          try {
              return Optional.ofNullable(Bootstrap
                      .getService(MonetaryCurrenciesSingletonSpi.class)).orElseGet(
                      DefaultMonetaryCurrenciesSingletonSpi::new);
          } catch (Exception e) {
              Logger.getLogger(Monetary.class.getName())
                      .log(Level.INFO, "Failed to load MonetaryCurrenciesSingletonSpi, using default.", e);
              return new DefaultMonetaryCurrenciesSingletonSpi();
          }
      }
docs: The used {@link javax.money.spi.MonetaryCurrenciesSingletonSpi} instance.