Introduction :

"hibernate MappingException: Could not determine type for: java.util.Set"

I am currently in the process of working on a web project that combines Vaadin, Spring 3 and JPA 2 with the use of the reference implementation hibernate and suddenly I had a small problem that I think most geeks have java have this kind of problem: org.hibernate.MappingException: Could not determined the type for: java.util.Set, also the same with java.util.Collection and java.util.List, when using annotations @ OneToMany and @ ManyToOne.

The solution for this problem is very easy but requires a lot of google search, so make sure that all annotations are on attributes and not on the getters.