add currency details to transaction.rb

[tomekcieslar]

Hello

We need this for handling original currency, original currency amount and exchange rate.
Thanks for considering my PR.

You can find the definition in the XSD.

Thank you in advance

[tobischo]

Thank you for providing an MR to address #72

One thing I am wondering about: the MR is correct in adding a comment about the original amount and currency possibly being empty, e.g. in case InstdAmt is not set - as it is optional in the CAMT specification.
Semantically, when calling it original amount, it is not just mapping the field, but rather represents the amount that was used when triggering the transfer. For same currency transfers that would still be applicable though even if InstdAmt is empty.

I guess we could add that later though should it become necessary as long as the returned value is semantically correct.

[frantisekrokusek]

You mean when original_currency == currency, then we would not have original_amount nor original currency supplied because they are both the same with amount and currency right ?

I think indeed it can be handled in a separate PR if someone sees the necessity to do so. Personally I prefer having nil values so there is no potential bank logic in the gem.

[tobischo]

Released as v2.18.0 and closes #72