The InvoiceLine class doesn't have a reference to the Invoice class (it's a unidirectionnal ManyToOne relationship). Even if I make it bidirectionnal by adding a reference to the Invoice class in the InvoiceLine class I don't get the result I want because in the database the primary keys (id) of Invoice and Product doesn't migrate in the InvoiceLine table. I just get a foreign key of type VARBINARY.
What I want in the invoiceLine table is
subject: ManyToMany relationship with extra field in the joinTable