I have an instance of a pojo object with some properties set (lets say a customer with its name and id set). I know the object exists in the db.

Is there a way to complete the pojo with data from the db, i.e. load all other properties from the db into the pojo, but keep the ones that are already set -- they are assumed to be more up to date.

(I know, the alternative would be to load the object first and then set the values, but this is not an option here. I also know, I could write a query to retrieve all properies for that object individually and then copy them into the pojo, but I am looking for something more generic that would work for all my classes).

Is this either so trivial or so uncommon that no-one feels like answering?

Or is my description not understandable. Please, where are the Hibernate experts?

There isn't any function in hibernate for doing what you describe. There is QueryByExample which would allow you to query the database with the partially completed object you describe, but updateing the fields with the more current values is up to you.