Which dialect do you use?

I'm using PostgreSQL82Dialect and Hibernate does create the index with proper name, like this:

CREATE INDEX payment_payment_formalid_idx
  ON payment_payment
  USING btree
  (formalid COLLATE pg_catalog."default" );

however the index is not unique, that's the only issue.

BTW this bug is intended for Hibernate <= 4.2.x, i.e. up to JPA 2.0, excluding JPA 2.1. So @org.hibernate.annotations.Index is still used here.