avoid nullpointers in list-typed fields

[borisskert]

While using the smartanalytics server some NullpointerExceptions occured while iterating through lists provided of some fields. These changes could lower the possibility of occuring Nullpointers.

If you dont like this changes we should speak about the logic in the smartanalytics server.

[DG0lden]

This makes Sense, only if you make setters with Null-Check. Is it easier to use Lombok NonNull annotation on the field?

[borisskert]

I'm not sure whether some API consumers are setting null values implicitly (like via object-mappers) or explicitly. They are retrieving exceptions in this case and logic will break.
My change was only about to set default values if no setter is called. We got some nullpointer exceptions in smartanalytics-server thats the reason.

I know there have to be changes in smartanalytics-server and mutlibanking to make this more stable. But this here is a first little step in my opinion.