We have a domain model with complex (check) logic in the setter methods. This code should not be executed when an object is created and initialised. The requirement is that the OR mapper and the user execute different setter code. I know that Hibernate is able to access the fields directly but this is not recommend. Since it is not recommend there must be a way to do this, e.g. with a wrapper class.

Any ideas how to do that?

Accessing the fields directly is okay to solve your problem if you think it is okay for your environment. If you want to fiddle with property accessing in other creative ways, use a custom PropertyAccessor