I am trying to refresh the @ManyToMany relation but it gets cleared instead...

My Project class looks like this:

@Entity
public class Project {
    ...
    @ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    @JoinTable(name = "PROJECT_USER",
    joinColumns = @JoinColumn(name = "PROJECT_ID", referencedColumnName = "ID"),
    inverseJoinColumns = @JoinColumn(name = "USER_ID", referencedColumnName = "ID"))
    private Collection<User> users;
    ...
}

But I don't have - and I don't want - the collection of Projects in the User entity.

When I look at the generated database tables, they look good. They contain all columns and constraints (primary/foreign keys).

But when I persist a Project that has a list of Users (and the users are still in the database), the mapping table doesn't get updated gets updated but when I refresh the project afterwards, the list of Users is cleared.

For better understanding:

Project project = ...; // new project with users that are available in the db
System.out.println(project getUsers().size()); // prints 5
em.persist(project);
System.out.println(project getUsers().size()); // prints 5
em.refresh(project);
System.out.println(project getUsers().size()); // prints 0

So, how can I refresh the relation between User and Project?