I did also some live coding during the talk and mentioned some things only verbally. Nevertheless I thought the slides (which are in German) might be of interest, so I decided to put them online.
You can also find the presentation at slideshare.
The talk went pretty well, there were many questions and people generally seemed quite interested :-) One question related to the automatic validation of constraints at JPA entities I couldn't answer immediately, though.
The question was, whether lazy properties are loaded from the database during validation of class-level constraints (for constraint validation at fields/properties lazy attributes must not be loaded, which is ensured by checking each attribute's load state using a TraversableResolver).
Actually this can happen, depending on the attributes accessed by the validator implementation for the class-level constraint. I think, generally this is alright, as the validator needs to know the values of all attributes relevant for the evaluation of the constraint. If in certain scenarios this behavior is not acceptable, one could examine the attributes' load states manually using javax.validation.PersistenceUtil and depending on that access only certain attributes.