Revert "add required user and pass"

This reverts commit 351f238.

controllers/factory/alertmanager/config.go

@@ -744,22 +744,27 @@ func (cb *configBuilder) buildHTTPConfig(httpCfg *operatorv1beta1.HTTPConfig) (y
 
 func (cb *configBuilder) buildBasicAuth(basicAuth *operatorv1beta1.BasicAuth) (yaml.MapSlice, error) {
 	var r yaml.MapSlice
-	u, err := cb.fetchSecretValue(&basicAuth.Username)
-	if err != nil {
-		return nil, err
-	}
-	r = append(r, yaml.MapItem{
-		Key:   "username",
-		Value: string(u),
-	})
-	p, err := cb.fetchSecretValue(&basicAuth.Password)
-	if err != nil {
-		return nil, err
-	}
-	r = append(r, yaml.MapItem{
-		Key:   "password",
-		Value: string(p),
-	})
+
+  if basicAuth.Username != nil {
+		u, err := cb.fetchSecretValue(&basicAuth.Username)
+		if err != nil {
+			return nil, err
+		}
+		r = append(r, yaml.MapItem{
+			Key:   "username",
+			Value: string(u),
+		})
+  }
+  if basicAuth.Password != nil {
+		p, err := cb.fetchSecretValue(&basicAuth.Password)
+		if err != nil {
+			return nil, err
+		}
+		r = append(r, yaml.MapItem{
+			Key:   "password",
+			Value: string(p),
+		})
+  }
   if len(basicAuth.PasswordFile) > 0 {
 		r = append(r, yaml.MapItem{
 			Key:   "password_file",