N°3169 - Add feature to connect Gsuite mail box with OAuth

N°2504 - Add feature to connect Office mail box with OAuth2 for Microsoft Graph
N°5102 - Allow to send emails (eg. notifications) using GSuite SMTP and OAuth
 * 2.7 migration (wip)

lib/guzzlehttp/promises/src/TaskQueueInterface.php

@@ -0,0 +1,24 @@
+<?php
+
+namespace GuzzleHttp\Promise;
+
+interface TaskQueueInterface
+{
+    /**
+     * Returns true if the queue is empty.
+     *
+     * @return bool
+     */
+    public function isEmpty();
+
+    /**
+     * Adds a task to the queue that will be executed the next time run is
+     * called.
+     */
+    public function add(callable $task);
+
+    /**
+     * Execute all of the pending task in the queue.
+     */
+    public function run();
+}