Release 4.0 of this library was made to introduce a breaking change:
* You now need to register your application with the Deutsche Kreditwirtschaft (German banking association) and supply
- your assigned product IT when initializing the library.
+ your assigned product ID when initializing the library.
The library used to have a built-in product ID that was used as a default if you didn't. This was very useful, but
Deutsche Kreditwirtschaft asked us to stop doing this, since it undermindes the whole point of the product registration.