I do not understand the use of the elements hsql key word. I am trying to form a query that compares to sets of data to see if there is a match:

I have a person which has groups and I have a user which has groups. The groups can either be active or inactive. I am trying to query for all persons that has any matching group from my user entity.

So one try:
from Person person where elemetns(from person.groups where person.groups.active = true) in elements(?)

then i set the parameter to user.getGroups()

That don't work. I have tried a million other variations, but honestly I am confused as to the best way to structure this query. Help appreciated. Essentially the idea is that i have the user object already and need a whole bunch of persons that have an intersection of the groups collection.