Treasury boolean set as column not updatable in order to prevent changes, to change, must use Update directly via using database a query
Currency not implemented, but initial design was either:
using an API for getting exchange rates and only saving into Account model the name of the currency, creating ExhangeRateService
creating another table Currencies with columns name, and code of currency and then have a ManyToOne relationship between Account and Currency (There is a branch called feature/currency with the partial implementation)