JPA (Hibernate) and postgres sql upsert using native query

Question

I would like to perform a batch upgrade with JPA and Postgres. I cannot use merging, as I am checking the conflict on a unique Constraint that is not PK. I found that for updating in postgres we can now use ON Conflict functionality. So basically I would like to execute my own query execution in JPA . The request will look like this:

 INSERT INTO user (user_id, display_name ) VALUES('1', 'sg27') ON CONFLICT (user_id) DO UPDATE SET display_name = 'sg27' RETURNING *; 

I will loop over the list of objects and make a query.

So, my question is when the inline insert of the request, we can use manual cleaning, for example em.flush() . Will it work for batch insertion.

If not, then someone please tell me what are the possible solutions to this problem?

Thank you for your time.