Changed CreationDate to string to prevent scientific notation convers…

…ion (#42053)

* Changed CreationDate to string to prevent scientific notation conversion

* Added changelog entry

* Make update

CHANGELOG.next.asciidoc

@@ -229,6 +229,7 @@ https://github.com/elastic/beats/compare/v8.8.1\...main[Check the HEAD diff]
 - Do not report non-existant 0 values for RSS metrics in docker/memory {pull}41449[41449]
 - Log Cisco Meraki `getDevicePerformanceScores` errors without stopping metrics collection. {pull}41622[41622]
 - Don't skip first bucket value in GCP metrics metricset for distribution type metrics {pull}41822[41822]
+- Fixed `creation_date` scientific notation output in the `elasticsearch.index` metricset. {pull}42053[42053]
 
 
 *Osquerybeat*

metricbeat/module/elasticsearch/index/data.go

@@ -20,7 +20,6 @@ package index
 import (
 	"encoding/json"
 	"fmt"
-	"strconv"
 
 	"github.com/joeshaw/multierror"
 
@@ -44,7 +43,7 @@ type Index struct {
 	Index          string     `json:"index"`
 	Status         string     `json:"status"`
 	TierPreference string     `json:"tier_preference"`
-	CreationDate   int        `json:"creation_date"`
+	CreationDate   string     `json:"creation_date"`
 	Version        string     `json:"version"`
 	Shards         shardStats `json:"shards"`
 }
@@ -307,10 +306,7 @@ func addIndexSettings(idx *Index, indicesSettings mapstr.M) error {
 		return fmt.Errorf("failed to get index creation date: %w", err)
 	}
 
-	idx.CreationDate, err = strconv.Atoi(indexCreationDate)
-	if err != nil {
-		return fmt.Errorf("failed to convert index creation date to int: %w", err)
-	}
+	idx.CreationDate = indexCreationDate
 
 	indexTierPreference, err := getIndexSettingForIndex(indexSettings, idx.Index, "index.routing.allocation.require._tier_preference")
 	if err != nil {