ExchangeRateProvider method parameters

[chsagynov]

In the ExchangeRateProvider interface, we have a getExchangeRate(string $sourceCurrencyCode, string $targetCurrencyCode) method. Can we change the parameter type to getExchangeRate(Currency $sourceCurrency, Currency $targetCurrency)? I'm guessing most databases use an int ID rather than a CODE string. In our case, we need to add some unnecessary relationships when fetching from the database. Also, the internal database may use an internal incremental ID instead of the ISO ID.