NHibernate Criteria Query - Select Distinct with Joined Entity

I have a Person entity. Every person has a country, I want to select all the distinct countries that have people in them. This Criteria Query returns all the distinct CountryID's

criteria.SetProjection(Projections.Distinct(Projections.Property("Country")));开发者_开发百科

How do I alter it to join and fetch the Country entity, not just the ID?

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Any easy way would be to use a subquery. That is, you could select the whole country on the outer query where the country ID matches the inner query.

Subqueries.PropertyIn(
  "Country",
  innerDetachedCriteriaWhichFindsCountriesWithPeopleAndProjectsCountryId)