NullPointerException on getProviderName() even when provider name exists #100

The following code generates a query successfully

CurrencyQuery query = CurrencyQueryBuilder.of().setProviderName("ProviderClassName").setCurrencyCodes("CNH").build();

But when the appropriate CurrencyProvider imp is loaded and getCurrencies(CurrencyQuery) is invoked, the following code results into NPE.

if (!query.isEmpty() && query.getProviderName().equals("SomeName")) {

      for (CurrencyUnit c : currencySet) {

          if (c.getCurrencyCodes().equals(query.getCurrencyCodes()) {

             return Collections.singleton(c);

          }

     }

}

We are always building the currency query such that it will have a provider name and currency unit. The above code results into an NPE for getProviderName() where a provider name actually exists.