1. 现象

2. 分析定位

原因：查看依赖项的级联关系，发现rest-high-level-client这个7.15.2包,的引用了6.4.3的rest-client。

3. 解决方案

直接把rest-client包的7.15.2版本的依赖项加进来就好了。
springboot集成es7

    <!-- https://mvnrepository.com/artifact/org.elasticsearch.client/elasticsearch-rest-client --><dependency><groupId>org.elasticsearch.client</groupId><artifactId>elasticsearch-rest-client</artifactId><version>7.15.2</version></dependency><!-- https://mvnrepository.com/artifact/org.elasticsearch/elasticsearch --><dependency><groupId>org.elasticsearch</groupId><artifactId>elasticsearch</artifactId><version>7.15.2</version></dependency><!-- https://mvnrepository.com/artifact/org.elasticsearch.client/elasticsearch-rest-high-level-client --><dependency><groupId>org.elasticsearch.client</groupId><artifactId>elasticsearch-rest-high-level-client</artifactId><version>7.15.2</version></dependency>