in a Domain, how to define a compound join involving a constant

I am looking at an embedded JasperServer environment for the first time, and attempting to create a simple domain to understand the end-to-end process.

In the transactional db there is a captions table that carries a foreign key and the table_name relevant to that foreign key. While It is simple enough to add this captions table into the domain, I don't see a way to create a join along these lines:

SELECT *
FROM some_table t
INNER JOIN captions_table ct ON t.id = ct.fk
              AND ct.table_name = 'SOME_TABLE'   --<< this predicate

It is that last predicate I don't see a solution for through the UI.

I can of course define a "derived table" but was rather hoping I would not have to do that for every table needing captions.

Jaspersoft Version/Build 6.1_5.1.0.26