Add detailed scanner trace output and notifications (#16668)

cmd/object-multipart-handlers.go

@@ -1019,7 +1019,7 @@ func (api objectAPIHandlers) CompleteMultipartUploadHandler(w http.ResponseWrite
 	writeSuccessResponseXML(w, encodedSuccessResponse)
 
 	// Notify object created event.
-	sendEvent(eventArgs{
+	evt := eventArgs{
 		EventName:    event.ObjectCreatedCompleteMultipartUpload,
 		BucketName:   bucket,
 		Object:       objInfo,
@@ -1027,7 +1027,13 @@ func (api objectAPIHandlers) CompleteMultipartUploadHandler(w http.ResponseWrite
 		RespElements: extractRespElements(w),
 		UserAgent:    r.UserAgent(),
 		Host:         handlers.GetSourceIP(r),
-	})
+	}
+	sendEvent(evt)
+
+	if objInfo.NumVersions > dataScannerExcessiveVersionsThreshold {
+		evt.EventName = event.ObjectManyVersions
+		sendEvent(evt)
+	}
 
 	// Remove the transitioned object whose object version is being overwritten.
 	if !globalTierConfigMgr.Empty() {