Adding distinct on to PostgreSQL

How do I add `DISTINCT ON (columns)` to SELECT clause?
I want to make this query:
`SELECT DISTINCT ON (testdummies.id) testdummies.id, testdummies.integer_array, testdummies.name FROM testdummies LEFT JOIN testdummies t0 ON (t0.id = ANY(testdummies.test_dummies) AND t0.name IN ('test2', 'test3') ) WHERE ((testdummies.private = false) OR (testdummies.private IS NULL)) AND t0.name IN ('test2', 'test3') LIMIT 10`

I have looked at the prepareSQL function :
https://github.com/JetBrains/Exposed/blob/master/src/main/kotlin/org/jetbrains/exposed/sql/Query.kt#L159-L208

It doesn't look like I can supply a list of distinct columns. Is there another method that can do this?