Jmeter 使用beanshell报错

相拼一个传参的用的结果，
代码如下：

log.info("工厂交接单号数量：" + vars.get("list4_matchNr" ) );
int num = Integer.valueOf("${list4_matchNr}");
log.info("num：" + num);
String list4 = "";


for(i=1; i<=num; i++){
    String list4Id = vars.get("list4_" + i); 
    log.info("list4Id为："+ vars.get("list4_" + i));
    list4s += list4Id + ",";
    }
list4s = list4s.substring(0,list4s.lenght() - 1);

log.info("list4s为：" + list4s);

vars.put("list4s" , list4s);

报错是这个：

ERROR o.a.j.u.BeanShellInterpreter: Error invoking bsh method: eval Sourced file: inline evaluation of: ``import JmeterAutomation;  log.info("工厂交接单号数量：" + vars.get("list4_matchNr" ) ); i . . . '' : Illegal use of undefined object or 'void' literal

找了半天没发解决有了解的仁兄吗？

https://www.cnblogs.com/puresoul/p/4949889.html

list4s ，没有看到这个变量声明的地方

String list4 = "";

改成
String list4s = "";

可以使用vars.putObject,
vars.put默认参数是String