docs: public AbstractExpression parseExpressionTree(VoltXMLElement root) {
          AbstractExpression expr = parseExpressionNode(root);
  
          // If there were any subquery expressions appearing in a scalar context,
          // we must wrap them in ScalarValueExpressions to avoid wrong answers.
          // See ENG-8226.
          expr = ExpressionUtil.wrapScalarSubqueries(expr);
          return expr;
      }