I have many-to-many relationship between User and Role entities in my DB schema. That is done through UserRole table. User-UserRole-Role

I use @JoinTable annotation to join all roles of a user.
Roles are fetching correctly, but when i try to persist new user with a set of roles i get an error:

2015-07-08 12:07:08 ERROR SqlExceptionHelper:146 - NULL not allowed for column "ID"; SQL statement:
insert into T_USER_ROLE (USER_ID, ROLE_ID) values (?, ?) [23502-176]

Because the generated insert script does not use sequence generator and does not provide T_USER_ROLE.ID value.

But if i persist UserRole directly in my code it works.

Please find a test case attached.
Best regards, Alexey.