presto-main/src/main/java/io/prestosql/sql/planner/iterative/rule/LambdaCaptureDesugaringRewriter.java/Visitor/rewriteSymbolReference
class Visitor:        @Override
        public Expression rewriteSymbolReference(SymbolReference node, Context context, ExpressionTreeRewriter<Context> treeRewriter)
        {
            context.getReferencedSymbols().add(new Symbol(node.getName()));
            return null;
        }