feat: add an ISO formatted timestamp in documents

nifi-provenance-reporting-tasks/src/main/java/io/egm/nifi/reporting/ElasticsearchProvenanceReporter.java

@@ -35,6 +35,8 @@
 import java.io.IOException;
 import java.net.MalformedURLException;
 import java.net.URL;
+import java.text.SimpleDateFormat;
+import java.util.Date;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -63,6 +65,7 @@ public class ElasticsearchProvenanceReporter extends AbstractProvenanceReporter
 
     private final Map<String, ElasticsearchClient> esClients = new HashMap<>();
     private final ObjectMapper objectMapper = new ObjectMapper();
+    private final SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
 
     private ElasticsearchClient getElasticsearchClient(String elasticsearchUrl) throws MalformedURLException {
         if (esClients.containsKey(elasticsearchUrl))
@@ -98,8 +101,11 @@ public void indexEvent(final Map<String, Object> event, final ReportingContext c
             return;
         }
 
+        final Long eventTimeMillis = (Long) event.get("event_time");
+
         Map<String, Object> preparedEvent = new HashMap<>();
-        preparedEvent.put("event_time", event.get("event_time"));
+        preparedEvent.put("event_time", eventTimeMillis);
+        preparedEvent.put("event_time_iso", sdf.format(new Date(eventTimeMillis)));
         preparedEvent.put("component_type", event.get("component_type"));
         preparedEvent.put("component_url", event.get("component_url"));
         preparedEvent.put("component_name", event.get("component_name"));