Hi Ben,

thank you to have submitted the issue.

I tried to reproduce the case in https://github.com/fax4ever/hibernate-play/tree/master/hibernate-compositeid-play.

The strategy you’re using is Identity, here is its description according to JPA:

/**
 * Indicates that the persistence provider must assign 
 * primary keys for the entity using a database identity column.
 */
IDENTITY

but we should have a multiple column primary key with a composite id:

create table EVNT_MILSTN (
  EVNT_ID bigint not null, 
  EVNT_MILSTN_ID bigint not null, 
  primary key (EVNT_ID, EVNT_MILSTN_ID)
)

Using an other strategy it seems work out.

But maybe I did reproduce exactly your case, since I had to extend the code you provided.

Let me know if that can make sense for you.

Thank you again

Fabio