write debug msg for successful ElasticSearchMetricSender _bulk POST request

Author: Dušan Markovič

src/main/java/io/github/delirius325/jmeter/backendlistener/elasticsearch/ElasticSearchMetricSender.java

@@ -151,11 +151,14 @@ public void sendRequest(int elasticSearchVersionPrefix) {
 
             Response response = this.client.performRequest(setAuthorizationHeader(request));
 
-            if (response.getStatusLine().getStatusCode() != HttpStatus.SC_OK && logger.isErrorEnabled()) {
-                logger.error("ElasticSearch Backend Listener failed to write results for index {}. Response status: {}",
-                             this.esIndex, response.getStatusLine().toString());
-            } else {
-                logger.debug("ElasticSearch Backend Listener has successfully written results for index {}", this.esIndex);
+            if (logger.isErrorEnabled()) {
+                if (response.getStatusLine().getStatusCode() != HttpStatus.SC_OK) {
+                    logger.error("ElasticSearch Backend Listener failed to write results for index {}. Response status: {}",
+                                 this.esIndex, response.getStatusLine().toString());
+                } else {
+                    logger.debug("ElasticSearch Backend Listener has successfully written to ES instance [{}] _bulk request {}",
+                                 client.getNodes().iterator().next().getHost().toHostString(), request.toString());
+                }
             }
         } catch (Exception e) {
             if (logger.isErrorEnabled()) {

src/main/java/io/github/delirius325/jmeter/backendlistener/elasticsearch/ElasticsearchBackendClient.java

@@ -1,4 +1,4 @@
-package io.github.delirius325.jmeter.backendlistener.elasticsearch;
+    package io.github.delirius325.jmeter.backendlistener.elasticsearch;
 
 import java.util.*;
 import java.util.regex.Matcher;
@@ -11,7 +11,6 @@
 import org.apache.jmeter.samplers.SampleResult;
 import org.apache.jmeter.util.JMeterUtils;
 import org.apache.jmeter.visualizers.backend.AbstractBackendListenerClient;
-import org.apache.jmeter.visualizers.backend.BackendListener;
 import org.apache.jmeter.visualizers.backend.BackendListenerContext;
 import org.elasticsearch.client.Node;
 import org.elasticsearch.client.RestClient;