code: @Override
      public List<String> getDefaultProviderChain() {
          List<String> list = new ArrayList<>(getProviderNames());
          return list;
      }
docs: Access a list of the currently registered default providers. The default providers are used, when
  no provider names are passed by the caller.
  
  @return the currencies returned by the given provider chain. If not provider names are provided
  the default provider chain configured in {@code javamoney.properties} is used.
  @see #getCurrencies(String...)
  @see CurrencyQueryBuilder