Empty `Set<Long>` is passed as `null`

[kevinm416]

I have a repository method:

  @org.springframework.data.jpa.repository.Query(
      nativeQuery = true,
      value = """
          SELECT cast(:productIds as TEXT) IS NULL
          """
  )
  boolean sanityCheck(Set<Long> productIds);

When I pass in an empty set, the empty set is converted to null somewhere before it makes it to the DB (Postgres):

Query:["SELECT cast((null) as TEXT) IS NULL
"], Params:[()]

Is this behavior documented anywhere? I don't understand why this would be expected or desirable.

[mp911de]

You might want to ask the Hibernate team.

entityManager.createNativeQuery("SELECT cast(:productIds as TEXT) IS NULL")
		.setParameter("productIds", Set.of())
		.getResultList();

gives me the same result.

Generally speaking, I'm not quite sure how useful such an arrangement is because what should an empty collection render to?