presto-main/src/main/java/io/prestosql/sql/planner/iterative/rule/ExpressionRewriteRuleSet.java/ProjectExpressionRewrite/apply
class ProjectExpressionRewrite:        @Override
        public Result apply(ProjectNode projectNode, Captures captures, Context context)
        {
            Assignments assignments = projectNode.getAssignments().rewrite(x -> rewriter.rewrite(x, context));
            if (projectNode.getAssignments().equals(assignments)) {
                return Result.empty();
            }
            return Result.ofPlanNode(new ProjectNode(projectNode.getId(), projectNode.getSource(), assignments));
        }