docs: protected void getTablesAndIndexesFromSubqueries(Map<String, StmtTargetTableScan> tablesRead,
              Collection<String> indexes) {
          for(AbstractExpression expr : findAllSubquerySubexpressions()) {
              assert(expr instanceof AbstractSubqueryExpression);
              AbstractSubqueryExpression subquery = (AbstractSubqueryExpression) expr;
              AbstractPlanNode subqueryNode = subquery.getSubqueryNode();
              assert(subqueryNode != null);
              subqueryNode.getTablesAndIndexes(tablesRead, indexes);
          }
      }