Persist created and updated time in compose

Also use the correct time format.

fakestorage/object_test.go

@@ -2065,6 +2065,7 @@ func TestServiceClientComposeObject(t *testing.T) {
 	)
 	u32Checksum := uint32Checksum([]byte(source1Content))
 	hash := checksum.MD5Hash([]byte(source1Content))
+	now := time.Now()
 
 	objs := []Object{
 		{
@@ -2198,6 +2199,12 @@ func TestServiceClientComposeObject(t *testing.T) {
 				if attrs.ContentType != contentType {
 					t.Errorf("wrong content type\nwant %q\ngot  %q", contentType, attrs.ContentType)
 				}
+				if now.After(attrs.Created) {
+					t.Errorf("wrong created time\nwant < %v\ngot:  %v", now, attrs.Created)
+				}
+				if now.After(attrs.Updated) {
+					t.Errorf("wrong updated time\nwant < %v\ngot:  %v", now, attrs.Updated)
+				}
 				if !bytes.Equal(attrs.MD5, expectedHash) {
 					t.Errorf("wrong hash returned\nwant %d\ngot   %d", hash, attrs.MD5)
 				}

internal/backend/fs.go

@@ -448,12 +448,14 @@ func (s *storageFS) ComposeObject(bucketName string, objectNames []string, desti
 		sourceObjects = append(sourceObjects, obj)
 	}
 
+	now := time.Now().Format(timestampFormat)
 	dest := StreamingObject{
 		ObjectAttrs: ObjectAttrs{
 			BucketName:  bucketName,
 			Name:        destinationName,
 			ContentType: contentType,
-			Created:     time.Now().String(),
+			Created:     now,
+			Updated:     now,
 		},
 	}
 

internal/backend/memory.go

@@ -361,12 +361,14 @@ func (s *storageMemory) ComposeObject(bucketName string, objectNames []string, d
 	var dest Object
 	streamingDest, err := s.GetObject(bucketName, destinationName)
 	if err != nil {
+		now := time.Now().Format(timestampFormat)
 		dest = Object{
 			ObjectAttrs: ObjectAttrs{
 				BucketName:  bucketName,
 				Name:        destinationName,
 				ContentType: contentType,
-				Created:     time.Now().String(),
+				Created:     now,
+				Updated:     now,
 			},
 		}
 	} else {