Mono repo -> Master (#22553)

Combines the following repositories into one:

https://github.com/mattermost/mattermost-server
https://github.com/mattermost/mattermost-webapp
https://github.com/mattermost/focalboard
https://github.com/mattermost/mattermost-plugin-playbooks

server/channels/api4/data_retention_test.go

@@ -0,0 +1,19 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package api4
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestDataRetentionGetPolicy(t *testing.T) {
+	th := Setup(t)
+	defer th.TearDown()
+
+	_, resp, err := th.Client.GetDataRetentionPolicy()
+	require.Error(t, err)
+	CheckNotImplementedStatus(t, resp)
+}