[FEATURE] extract primary keys from ALTER TABLE .. ADD CONSTRAINT.. . PRIMARY KEY (...); #1817

Hi,

When parsing a CREATE TABLE, we have built-in functions to retrieve the PRIMARY KEYS in JSQLParser.

But in the case where the CREATE TABLE does not contain the PRIMARY KEYS, which are added later with an ALTER TABLE:

CREATE TABLE public.staff (
    staff_id integer DEFAULT nextval('public.staff_staff_id_seq'::regclass) NOT NULL,
    first_name character varying(45) NOT NULL,
    last_name character varying(45) NOT NULL,
    address_id smallint NOT NULL,
    email character varying(50),
    store_id smallint NOT NULL,
    active boolean DEFAULT true NOT NULL,
    username character varying(16) NOT NULL,
    password character varying(40),
    last_update timestamp without time zone DEFAULT now() NOT NULL,
    picture bytea
);

Done later in file:

ALTER TABLE ONLY public.staff
    ADD CONSTRAINT staff_pkey PRIMARY KEY (staff_id);

I can't figure out how to retrieve the PRIMARY KEYS without doing manual parsing of the ALTER TABLE.
Is there a way in JSQLParser?

I have tried this attached code, but it prints null values.
PrimaryKeyExtractorTest.java.txt

(I can't in my case just move the PRIMARY KEYS creation in the staff table, because I write a schema displayer that takes in new schemas texts that I know nothing about).

Thanks,
Nicolas