Elasticsearch 6.x 版本彻底移除string了
另外，index的值只能是boolean变量了。
junit java 测试单元
自己写的博客链接： https://blog.csdn.net/qq_37114789/article/details/105904308
参考了以下大佬们的博客文章：
https://blog.csdn.net/Mr_OOO/article/details/79518978
https://blog.csdn.net/qq_38796327/article/details/90480314
https://www.cnblogs.com/biehongli/p/11710704.html
https://www.cnblogs.com/chenyuanbo/p/10296809.html
https://blog.csdn.net/fulishafulisha/article/details/80158392