Issue reproduction

```
create table foo (id int primary key, hs public.hstore DEFAULT ''::public.hstore NOT NULL);
insert into foo values (18, 'a=>1'::hstore);
```

Start debezium with "hstore.handling.mode": "map"

I can see a crash: Unexpected value for JDBC type 1111 and column config hstore(2147483647, 0) NOT NULL: class=java.util.HashMap

This is related to the fact that, in snapshot mode, the hstore column arrives in convertHStore function as a Map. In stream mode, it's not the case.

I did not see any issue in JSON mode.

PR: https://github.com/debezium/debezium/pull/4490