code: @Override
      public Set<String> getProviderNames() {
          Set<String> result = new HashSet<>();
          for (RoundingProviderSpi prov : Bootstrap.getServices(RoundingProviderSpi.class)) {
              try {
                  result.add(prov.getProviderName());
              } catch (Exception e) {
                  Logger.getLogger(Monetary.class.getName())
                          .log(Level.SEVERE, "Error loading RoundingProviderSpi from provider: " + prov, e);
              }
          }
          return result;
      }
docs: Get the names of all current registered providers.
  
  @return the names of all current registered providers, never null.