@Entity
public class UserEntity implements Serializable {
    /*...*/
    @ManyToMany(mappedBy = "owners")
    private List<AppEntity> ownedApps;
    
    public List<AppEntity> getOwnedApps() {
        return ownedApps;
    }

    /*...*/
}

@Entity
public class AppEntity implements Serializable {
    /*...*/
    @ManyToMany
    private List<UserEntity> owners;

    public void addOwner(UserEntity owner) {
        owners.add(owner);
    }

    public List<UserEntity> getOwners() {
        return owners;
    }

    /*...*/
}

@Singleton
@Startup
public class ConfigBean {
    /*...*/

    @PersistenceContext
    private EntityManager em;

    @PostConstruct
    public void createData() {
        /*...*/
        UserEntity admin = new UserEntity();
        em.persist(admin);
        AppEntity someapp = new AppEntity();
        em.persist(somegame);
        somegame.addOwner(admin);
        /*...*/
    }
}