Elasticsearch报错:java.lang.NoSuchMethodError: Could not initialize class org.elasticsearch.http.netty

Elasticsearch相关问题：

java.lang.NoClassDefFoundError: Could not initialize class org.elasticsearch.http.netty4.Netty4HttpServerTransport

	at org.elasticsearch.transport.Netty4Plugin.getSettings(Netty4Plugin.java:56)...

pom依赖相关：使用transport、elasticsearch

<dependency>
      <groupId>org.elasticsearch.client</groupId>
      <artifactId>transport</artifactId>
      <version>5.5.2</version>
 </dependency>
<dependency>
       <groupId>org.elasticsearch</groupId>
       <artifactId>elasticsearch</artifactId>
       <version>5.5.2</version>
</dependency>

或者是spring-boot-starter-data-elasticsearch时

<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-data-elasticsearch</artifactId>
</dependency>

原因：transport缺少netty4相关依赖

此处导入5.4.3版本

<dependency>
       <groupId>org.elasticsearch.plugin</groupId>
       <artifactId>transport-netty4-client</artifactId>
       <version>5.4.3</version>
</dependency>

导入后就能正常启动了