code: @Override
      public Set<String> getProviderNames() {
          Set<String> result = new HashSet<>();
          for (CurrencyProviderSpi spi : Bootstrap.getServices(CurrencyProviderSpi.class)) {
              try {
                  result.add(spi.getProviderName());
              } catch (Exception e) {
                  Logger.getLogger(DefaultMonetaryCurrenciesSingletonSpi.class.getName())
                          .log(Level.SEVERE, "Error loading currency provider names for " + spi.getClass().getName(),
                                  e);
              }
          }
          return result;
      }
docs: Get the names of the currently loaded providers.
  
  @return the names of the currently loaded providers, never null.