presto-main/src/main/java/io/prestosql/execution/scheduler/PhasedExecutionSchedule.java/PhasedExecutionSchedule/visitIndexJoin
class PhasedExecutionSchedule:        @Override
        public Set<PlanFragmentId> visitIndexJoin(IndexJoinNode node, PlanFragmentId currentFragmentId)
        {
            return processJoin(node.getIndexSource(), node.getProbeSource(), currentFragmentId);
        }