presto-main/src/main/java/io/prestosql/sql/planner/iterative/rule/PushProjectionThroughJoin.java/PushProjectionThroughJoin/inlineProjections
class PushProjectionThroughJoin:    private static PlanNode inlineProjections(ProjectNode parentProjection, Lookup lookup)
    {
        PlanNode child = lookup.resolve(parentProjection.getSource());
        if (!(child instanceof ProjectNode)) {
            return parentProjection;
        }
        ProjectNode childProjection = (ProjectNode) child;

        return InlineProjections.inlineProjections(parentProjection, childProjection)
                .map(node -> inlineProjections(node, lookup))
                .orElse(parentProjection);
    }