Solved.
After connected to the server, I just indexed one data like this:
server = new ServerBuilder().
settings(ImmutableSettings.settingsBuilder().put(elasticSearchSettings).build()).server()
client = server.client()
try {
IndexResponse response = client.index(indexRequest("testing")
.type("testings")
.id("testings")
.source('{"testings":"testings"}')).actionGet()
} catch(Exception e) {
throw new ElasticSearchException("ElasticSearch doesn't work with settings: ${elasticSearchSettings}")
}
println "Connected to ElasticSearch Server with settings: ${elasticSearchSettings}"