private IterableChecker<List<String>, String> ids(DateHolderCriteria criteria) {
    return CriteriaChecker.<TypeHolder.DateHolder>ofReader(repository.find(criteria)).toList(TypeHolder.DateHolder::id);
  }
Testing predicates, projections, sorting etc. on booleans
criteria/common/test/org/immutables/criteria/typemodel/DateTemplate.java