addDuplicateFilter example

        $query = $this->getIdsQuery($criteria, $context);
        $duplicateFilter = $request->get('duplicateFilter', false);
        $emptyFilter = $request->get('emptyFilter', false);
        $assignmentFilter = $request->get('assignmentFilter', false);

        if ($emptyFilter) {
            $this->addEmptyFilter($query);
        }

        if ($duplicateFilter) {
            $this->addDuplicateFilter($query);
        }

        if (\is_array($assignmentFilter)) {
            $this->addAssignmentFilter($query, $assignmentFilter);
        }

        $ids = $query->executeQuery()->fetchFirstColumn();

        return new FilteredTagIdsStruct($ids, $this->getTotal($query));
    }