code: public static CurrencyConversion getConversion(CurrencyUnit termCurrency, String... providers){
          Objects.requireNonNull(providers);
          Objects.requireNonNull(termCurrency);
          if(providers.length == 0){
              return getMonetaryConversionsSpi().getConversion(
                      ConversionQueryBuilder.of().setTermCurrency(termCurrency).setProviderNames(getDefaultConversionProviderChain())
                              .build());
          }
          return getMonetaryConversionsSpi().getConversion(
                  ConversionQueryBuilder.of().setTermCurrency(termCurrency).setProviderNames(providers).build());
      }
docs: Access an instance of {@link CurrencyConversion} for the given providers.
  Use {@link #getConversionProviderNames()} to check, which are available.
  
  @param termCurrency the terminating or target currency, not {@code null}
  @param providers    Additional providers, for building a provider chain
  @return the exchange rate type if this instance.
  @throws IllegalArgumentException if no such {@link ExchangeRateProvider} is available.