java.lang.NoClassDefFoundError: org/elasticsearch/script/mustache/SearchTemplateRequest

Question

I am trying to access Amazon Elasticsearch instance using the RestHighLevelClient from a java program. Below is my code:

AWS4Signer signer = new AWS4Signer();
signer.setServiceName("es");
signer.setRegionName("us-east-1");
HttpRequestInterceptor interceptor = new AWSRequestSigningApacheInterceptor("es", signer, creds);            

RestHighLevelClient EsClient = new RestHighLevelClient(RestClient.builder(new HttpHost("hostname.us-east-1.es.amazonaws.com",443,"https"))
.setHttpClientConfigCallback(httpAsyncClientBuilder -> HttpAsyncClientBuilder
.create()
.addInterceptorLast(interceptor)));

When I run this code, I am seeing this error:

Exception in thread "main" java.lang.NoClassDefFoundError: org/elasticsearch/script/mustache/SearchTemplateRequest
    at Main.main(Main.java:194)
Caused by: java.lang.ClassNotFoundException: org.elasticsearch.script.mustache.SearchTemplateRequest
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 1 more

This is happening at the initialization of EsClient. The error indicates a missing dependency, but I do have org.elasticsearch.script in my classpath. However, it doesn't seem to have the mustache.SearchTemplateRequest. Below are the relevant dependencies I have added to the project:

Not sure what I am missing here. Any help would be appreciated. Thank you.

Answer 1

I was missing the below jar:

<!-- https://mvnrepository.com/artifact/org.elasticsearch.plugin/lang-mustache-client -->
<dependency>
    <groupId>org.elasticsearch.plugin</groupId>
    <artifactId>lang-mustache-client</artifactId>
    <version>7.6.2</version>
</dependency>

There were several other jars that I had to add to finally get it working.