Query generator flattening algorithm bug (correlated array references in Join clause are not rewritten as subqueries)

For the following nested query, the flattened equivalent query should have a subquery for both a4 and a5. However a5 is not replaced with a subquery. The query generator incorrectly reports incorrect results for these kind of nested queries.

SELECT
 ...
FROM 
  table_1.field_19.value a1
WHERE
  123 IN (
    SELECT
      a5.item
    FROM
      a1.item.field_48.value.item a4
      INNER JOIN a1.item.field_22.item.field_36.field_38 a5
   )