presto-main/src/main/java/io/prestosql/sql/planner/plan/JoinNode.java/JoinNode/flipChildren
class JoinNode:    public JoinNode flipChildren()
    {
        return new JoinNode(
                getId(),
                flipType(type),
                right,
                left,
                flipJoinCriteria(criteria),
                flipOutputSymbols(getOutputSymbols(), left, right),
                filter,
                rightHashSymbol,
                leftHashSymbol,
                distributionType,
                spillable,
                ImmutableMap.of()); // dynamicFilters are invalid after flipping children
    }