presto-main/src/main/java/io/prestosql/sql/planner/iterative/rule/ReorderJoins.java/JoinEnumerator/getPossibleJoinNodes
class JoinEnumerator:        private List<JoinEnumerationResult> getPossibleJoinNodes(JoinNode joinNode, DistributionType distributionType)
        {
            return ImmutableList.of(
                    createJoinEnumerationResult(joinNode.withDistributionType(distributionType)),
                    createJoinEnumerationResult(joinNode.flipChildren().withDistributionType(distributionType)));
        }