Fix Retention, ObjectLock, LegalHold struct namespaces correctly. (#8909)

Reverts #8903 to allow structs to be unmarshalled 
even if the namespace is missing.

pkg/event/config.go

@@ -209,7 +209,8 @@ type topic struct {
 // Config - notification configuration described in
 // http://docs.aws.amazon.com/AmazonS3/latest/dev/NotificationHowTo.html
 type Config struct {
-	XMLName    xml.Name `xml:"http://s3.amazonaws.com/doc/2006-03-01/ NotificationConfiguration"`
+	XMLNS      string   `xml:"xmlns,attr,omitempty"`
+	XMLName    xml.Name `xml:"NotificationConfiguration"`
 	QueueList  []Queue  `xml:"QueueConfiguration,omitempty"`
 	LambdaList []lambda `xml:"CloudFunctionConfiguration,omitempty"`
 	TopicList  []topic  `xml:"TopicConfiguration,omitempty"`
@@ -290,6 +291,9 @@ func ParseConfig(reader io.Reader, region string, targetList *TargetList) (*Conf
 	}
 
 	config.SetRegion(region)
-
+	//If xml namespace is empty, set a default value before returning.
+	if config.XMLNS == "" {
+		config.XMLNS = "http://s3.amazonaws.com/doc/2006-03-01/"
+	}
 	return &config, nil
 }

pkg/event/config_test.go

@@ -433,7 +433,7 @@ func TestConfigUnmarshalXML(t *testing.T) {
 	`)
 
 	dataCase3 := []byte(`
-	<NotificationConfiguration  xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
+	<NotificationConfiguration>
 	   <QueueConfiguration>
 	      <Id>1</Id>
 	      <Filter></Filter>